[RPG] n official feat that gives expertise for weapons


I am playing, as well as about to start DM'ing a one shot, in fifth edition D&D and one of my soon-to-be players has talked to me about making either a Fighter (Samurai) or Monk (Kensei) and was wondering if there was any feat that acted like the Bard's "Expertise" class feature but for weapons rather then skills.

While I have found some homebrewed content for this, I haven't found anything official, but I just might not be looking in the right places. Is there something like this or at least a homebrew that is relatively balanced?

Edit: Rather then adding the bonus to attack roll I was looking for something that just effects Damage even if it was a just 1/rest effect. I know that "Great Weapon Master" effect is a -5 to hit, +10 to damage. But I was hoping that there was something like, all attacks deal x2 Proficiency Damage for this turn, 1/rest, so the "Arthur the Archer" example wouldn't effect his to hit chance just the damage he deals IF he hits.

Best Answer

There is no such official feat. Even in the Unearthed Arcana article that included weapon mastery feats, said weapon mastery feats only gave +1 to attack rolls with the weapon in question, rather than doubling your proficiency bonus.

More fundamentally, you asked whether there was any material doing this that's relatively balanced. The closest thing to what you're asking about is the Oath of Devotion Paladin's Sacred Weapon ability, which allows them to add their Charisma modifier to attack rolls. However, this is usable 1/rest, only lasts a minute, and requires an action to activate.

What you're asking about is an always-on bonus to attack rolls that starts at +2 and scales up to +6. No such ability, homebrewed or otherwise, could exist and be reasonably balanced. D&D 5e incorporates the concept of 'bounded accuracy', which means that numerical bonuses to attack rolls in particular are rare, and fairly small.

For a more practical example of why a feat like this can't be balanced, consider Arthur the Archer. Arthur is level 17, and has the Archery Fighting Style, a Dexterity score of 20, and your hypothetical feat. This gives him a bonus to attack rolls of +19. This means that, against the vast majority of enemies, Arthur can only miss if he rolls a 1 (since that's an automatic miss).

So why is this a problem? Because at high levels, everyone who's planning on using a weapon to fight has to have this feat. This isn't necessarily a bad thing - if you want a game where high-level characters almost never miss, introducing this feat and encouraging your players to take it will provide that. But in terms of balance with existing material, such a feat cannot be balanced.