Unarmed Strikes: Untangling the Rules
You're a monk who has reached 5th level and are excited about finally getting the Stunning Strike feature. But wait. Like many monks, you opt to rely just on your deadly hands in combat. The Stunning Strike feature, however, states: "When you hit another creature with a melee weapon attack, you can spend 1 ki point to attempt a stunning strike." (Emphasis added.) (PHB 79.) Are hands considered weapons? You check the Player's Handbook and, lo and behold, an unarmed strike is "a punch, kick, head-butt, or similar forceful blow (none of which count as weapons)." (Emphasis added.) (PHB 195.) What!? How can Stunning Strike, a Monk class feature, not apply to your unarmed strikes? That makes no sense.
Lucky for you, the Wizards of the Coast team agrees. Unfortunately, rather than revise the core rule itself as set forth in the PHB, they buried the fix on page 4 of a subsidiary document called the Sage Advice Compendium found on D&D Beyond. Dungeons & Dragons 5e rules are a bit of mess when it comes to "unarmed strikes." Let's try to sort things out, step-by-step.
A melee attack is hand-to-hand combat. It can be accomplished with a weapon, or with an improvised weapon (PHB 147, e.g., a frying pan), or with no weapon at all. The official definition: "Used in hand-to-hand combat, a melee attack allows you to attack a foe within your reach. A melee attack typically uses a handheld weapon such as a sword, a warhammer, or an axe." (PHB 95.) So far so good.
An unarmed strike is simply a melee attack without using a weapon. The official definition: "Instead of using a weapon to make a melee weapon attack, you can use an unarmed strike: a punch, kick, head-butt, or similar forceful blow (none of which count as weapons). On a hit, an unarmed strike deals bludgeoning damage equal to 1 + your Strength modifier. You are proficient with your unarmed strikes." (PHB 195.)
This rule makes sense on its face. Your fist may be a weapon in a colloquial sense, but for purposes of game mechanics, a weapon is something held in the hand (let's put aside for now the notion of "natural" weapons for monsters). The rule also addresses the issues of proficiency and damage for unarmed strikes. So far so good.
"MELEE ATTACK" RULES - NO PROBLEM
The first set of rules we review refers to the term "melee attack" (not "melee weapon attack") and makes no distinction between weapon strikes and unarmed strikes. These rules generally present no problem for us. For example:
Opportunity attack: "You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach." (PHB 195.)
This rule on its face does not preclude application to unarmed strikes and, furthermore, does not violate common sense. Jeremy Crawford, lead rules designer of D&D, states: "When you make an opportunity attack, you make a melee attack. The rule intentionally doesn't require a weapon. You can punch your foe with your fist, clobber them with a drumstick, whack them with a ladle, strike them with a sword, or deliver the attack in some other way."
Extra Attack class feature. For the Fighter class: "Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn. The number of attacks increases to three when you reach 11th level in this class and to four when you reach 20th level in this class."
This rule does not mention or require use of a weapon. And application of it to an unarmed strike does not violate common sense. SAC states: "When you use Extra Attack, do you have to use the same weapon for all the attacks? Extra Attack imposes no limitation on what you use for the attacks. You can use regular weapons, improvised weapons, unarmed strikes, or a combination of these options for the attacks." (SAC 3.)
One caveat. I'm not aware of any, but if there is a rule pertaining to a "melee attack" that does not mention weapon use but its application would not make sense if applied to an unarmed strike, then a DM should feel free not to apply the rule to unarmed strikes.
"MELEE WEAPON ATTACK" RULES - PROBLEM
Now we look at the rules that reference the term "melee weapon attack." It is the indiscriminate use of the word "weapon" that is the problem. Although some rules that reference "melee weapon attack" were meant to apply only to melee attacks that use a weapon, many rules that reference this term were not intended to preclude their application to unarmed strikes. This was an oversight, as Jeremy Crawford acknowledges.
Stunning Strike feature of the Monk class. "Starting at 5th level, you can interfere with the flow of ki in an opponent’s body. When you hit another creature with a melee weapon attack, you can spend 1 ki point to attempt a stunning strike. The target must succeed on a Constitution saving throw or be stunned until the end of your next turn." (PHB 79.)
The above rule indicates, at least on its face, that use of a weapon in the melee attack is necessary in order to attempt a stunning strike. That was not the intent of the rule. The Wizards of the Coast team fixed the problem, but as mentioned above did not revise the rule itself as set forth in the PHB and instead placed the fix in the SAC:
"Can a monk use Stunning Strike with an unarmed strike, even though unarmed strikes aren’t weapons? Yes. Stunning Strike works with melee weapon attacks, and an unarmed strike is a special type of melee weapon attack. The game often makes exceptions to general rules, and this is an important exception: that unarmed strikes count as melee weapon attacks despite not being weapons." (SAC 4.)
The exception to which the SAC refers is also set forth in the SAC:
"What does 'melee weapon attack' mean: a melee attack with a weapon or an attack with a melee weapon? It means a melee attack with a weapon. Similarly, 'ranged weapon attack' means a ranged attack with a weapon. Some attacks count as a melee or ranged weapon attack even if a weapon isn’t involved, as specified in the text of those attacks. For example, an unarmed strike counts as a melee weapon attack, even though the attacker’s body isn’t considered a weapon." (SAC 12.)
So there you have it: a punch, kick, head-butt, or similar forceful blow, none of which count as weapons, counts as a melee weapon attack. Linguistically awkward? Yes. But short of a rewrite of the core rules, there were few other options.
Jeremy Crawford's tweet provides additional guidance: "In fact, an unarmed strike can be used with any melee weapon attack, unless the text of that attack specifically mentions a weapon or something else that would make an unarmed strike impossible." (Emphasis added.). The last phrase in this sentence is not mentioned in the SAC but is important.
The SAC rule combined with Jeremy Crawford's clarification essentially solves the problem. It should be noted, however, that any particular rule that references "melee attack" or, especially, "melee weapon attack" will require a careful reading to determine whether it mentions a weapon or refers to something else that would make an unarmed strike impossible.
SUMMARY OF THE OFFICIAL RULES (WITH THE FIX)
The official rules on unarmed strikes are paraphrased as follows:
Summary of the Official Rules
A unarmed strike is a melee attacking without using a weapon, e.g., a punch, kick, head-butt, or similar forceful blow (none of which count as weapons). On a hit, an unarmed strike deals bludgeoning damage equal to 1 + your Strength modifier. You are proficient with your unarmed strikes." (PHB 195.)
A rule that references "melee attack" applies to an unarmed strike, unless something else would make an unarmed strike impossible. (See SAC 3.)
A rule that references "melee weapon attack" applies to an unarmed strike, unless: (1) the rule has a weapons-related qualifier; or (2) something else would make an unarmed strike impossible. (SAC 12; Jeremy Crawford tweet.
Even the fixed rules do not, to me, always make sense. Why should a rule that refers to the use of a weapon automatically preclude application of the rule to an unarmed strike? The reference to a weapon could have been gratuitous and not intended as any limitation.
The SAC admits to as much in the following example:
Divine Smite. "Can a paladin use Divine Smite when they hit using an unarmed strike? No. Divine Smite isn’t intended to work with unarmed strikes. Divine Smite does work with a melee weapon attack, and an unarmed strike can be used to make such an attack. But the text of Divine Smite also refers to the “weapon’s damage,” and an unarmed strike isn’t a weapon. If a DM decides to override this rule, no imbalance is created. Tying Divine Smite to weapons was a thematic choice on our part—paladins being traditionally associated with weapons. It was not a game balance choice." (SAC 5.)
I recommend the following house rule, which is intended to replace the official rules on the subject.
An unarmed strike can be used with any melee attack or melee weapon attack, unless the rule specifically mentions something that would make an unarmed strike impossible or defy common sense.
Here are examples of where I would allow a rule to be used with an unarmed strike even though the SAC says otherwise:
Savage Attacker feat. "Once per turn when you roll damage for a melee weapon attack, you can reroll the weapon’s damage dice and use either total."
Sage Advice Compendium states: "Does the Savage Attacker feat work with unarmed strikes? No. Savage Attacker relies on a weapon’s damage dice, and an unarmed strike isn’t a weapon (a point that was clarified in the Player’s Handbook errata). (SAC 9.)
This feat does mention "weapon" but, logically speaking, it is not clear to me why an unarmed strike would not benefit from the Savage Attacker feat. Couldn't you be savage with your fist? I would allow application of this feat to an unarmed strike. I don't think there would be any imbalance and it would be more fair.
Sneak Attack. "Can a rogue/monk use Sneak Attack with unarmed strikes? The Sneak Attack feature works with a weapon that has the finesse or ranged property. An unarmed strike isn’t a weapon, so it doesn’t qualify. In contrast, a rogue/ monk can use Sneak Attack with a monk weapon, such as a shortsword or a dagger, that has one of the required properties." (SAC 8.)
I see no reason why Sneak Attack could not be used with an unarmed strike. A finesse weapon is relatively light. Using no weapon and only a fist is even lighter.
DM discretion will have to be used whether with the official fixed rules or my house rule. With the above example with Divine Smite as a prime example, I think automatically precluding application of a feat, feature, magic, etc., that happens to mention a weapon in the description is not fair, does not balance the game, and serves no other purpose. Hence the house rule and the use of DM discretion.