Part of an ongoing series of 5e (2014) and 5.5e (2024) Rules notes.  

Something I often joke about here is how D&D is not a physics simulator, and, in fact, is a very mediocre tactical combat simulator.  All games, more or less, are, both because drama is more exciting than reality, and because reality is really hard to simulate

One of the things that D&D 5e (2014) brought to the mix was the KISS principle. Gone was to be the crunchity-crunch-crunch of multiple bonuses and penalties on rolls from the 3.5e period.  Gone was the slick but somewhat joyless tactical detail of 4e. Instead,  5e tried to keep it simple while at the same time making it fun.

By and large, not a bad job. Lots of abstractions, lots of handwaving about Advantage and Disadvantage, pretty good show.

5.5e (2024) for all its plusses and minuses, added a new element to combats by somewhat-popular demand — and which has turned out to be a lot more controversial than I would have expected.

Weapon Mastery!

A Longsword does 1d8 slashing damage.

A Flail does 1d8 bludgeoning damage.

A Morning Star does 1d8 piercing damage.

Are these the same?

Well, obviously not. A flail slams weights against its target.  A longsword slices and dices (and pierces, but we’ll ignore that for D&D). A morning star pokes little pokey bits backed by weight into its victim. The damage type is different — bludgeoning vs slashing vs piercing — but there is very, very little in the rules were that actually means anything (skeletons being vulnerable to bludgeoning weapons is the only thing that comes to mind).

Abstraction is useful, even necessary, to deal with real-world details that could easily overwhelm.  But too much abstraction is equally problematic. I once abandoned a super-heroes gaming system because there was no mechanical, in-game difference between someone attacking with a telekinetic blast, jet of flame, or lightning bolt. The same, to an extent, is true for weapons and their use.  If a flail = a longsword = a morning star in every way that counts except for your character picture — is that too much abstraction?

5.5e says, “Yeah, let’s see what we can do about that.”

Weapon Mastery?

The Weapon Mastery rules consist of two parts: What It Is and How To Get It

What Is Weapon Mastery?

Weapon Mastery is an additional aspect to weapons that certain characters can get by becoming “masters” of that particular weapon and learning to use its more interesting features.

If you look at the Weapons table, you can see the Mastery column that indicates how a trained user of the weapon can do something extra. That something extra, as spelled out by the rules, includes (with some weapon examples):

• Cleave: Once a turn, on a hit, the attacker does a follow-on attack on another target within 5 feet of the first and within reach. Damage on that second attack does not include the Ability modifier (unless negative). [Greataxe, Halberd]
• Graze:  If the attack misses, it still does damage equal to the attacker’s Ability modifier. [Glaive, Greatsword]
• Nick: When the attacker make an extra attack because the weapon is Light, they can do it as part of your Attack action, not using up their Bonus Action. [Scimitar, Dagger]
• Push:  On a hit, the attacker can push the target 10 feet away if size Large or smaller. [War Hammer, Heavy Crossbow]
• Sap: On a hit, the target has Disadvantage on its next attack roll. [Longsword, Morning Star]
• Slow:  On a hit with damage, the target’s Speed is reduced by 10 feet until your next turn (no stacking). [Club, Light Crossbow, Longbow]
• Topple:  On a hit, the target makes a CON Save vs DC (8 + attacker’s Ability Modifier + attacker’s Proficiency Bonus) or go Prone. [Maul, Quarterstaff]
• Vex: On a hit with damage, the attacker has Advantage on the next roll against that creature before the end of their next turn. [Short Bow, Rapier]

How Do I Get Weapon Mastery?

1. Various martial classes (Barbarian, Fighter, Paladin, Ranger, Rogue) automatically get at a Level 1 the Weapon Mastery class feature. This lets you use the Mastery feature of some (the number varies by class) simple or martial weapons of your choice. You can swap out for another one of these each Long Rest.  For some classes, the number of Weapon Masteries increases as levels go up.
2. The Weapon Master feat gives you an ASI and (to the point) lets you use the Mastery of one simple or martial weapon of your choice (which can be swapped around after any Long Rest) if you have Proficiency for it. This basically opens up the ability to non-martials.

Pros and Cons

The plus and minus of Weapon Mastery as a game rule is the same: It’s one more thing to do stuff with.

As a plus? It sets apart martials a bit more; it allows additional tactical elements in combat; it improves flavor by keeping flails and longswords and morning stars from all being the same.

As a minus? It slows down combat while tactical decisions are made (do I want to use the push-back? what path? does that mean it would be better to attack this other opponent? etc.); the mapping between the Masteries and the actual weapon is a bit sketchy, so the verisimilitude is strained.

I don’t have a net-net here, until I see how it works in actual gameplay.  To the extent that it adds some additional flavor to folks like Fighters (beyond “I hit him with my sword. And again. And again.”) it seems like it would be a good thing, but it’s easy to understand why some folk think it represents a creeping re-complexity for D&D combat.