Custom Magic Item Rarity

[proselus]

What rarity would you assign to a Heavy Crossbow that magically gave the attuned user access to the Crossbow Expert feat while wielding it (the hand crossbow bit not really applying here)? Essentially, how rare should a heavy crossbow that ignores loading and can be fired in melee be?

[leogobsin]

I would say uncommon- it seems about on par with a +1 weapon.

[Chaosvii7]

If you want to keep it in line with the rarity scale that published material use, I'd say rare - the feat represents someone being trained in using a crossbow, a weapon that can teach its wielder how to use it expertly without much prior knowledge is pretty above average, and uncommon is normally reserved for mundane effects (like the +1 to attack and damage rolls synonymous with uncommon-tier weapons).

But normally when I make an item specifically for someone, or make an item whose power I can't adequately judge vis a vis other magic items, I just call it Unique rarity. That could encompass anything from a tattoo that lets my player's ranger summon a bat, to a magical suit of wooden armour that's replaced the metal plating of a warforged hexblade.