Trying to create a homebrew item for Crossbows, and noticed there's no 'damage' option for crossbows, but is for shortbow and longbow. 

Tried copying bracers of archery and modify the proficiency and +2 damage bonus so it appears in the damage roll too. 

 https://www.dndbeyond.com/magic-items/4593-bracers-of-archery

Any tips?

You can’t because, as you noted, there’s no crossbow subtypes for the damage Modifier. You’ll have to make it as plain text, and the player will have to customize their crossbows directly on their character sheet.

Quote from IamSposta >>

You can’t because, as you noted, there’s no crossbow subtypes for the damage Modifier. You’ll have to make it as plain text, and the player will have to customize their crossbows directly on their character sheet.

 Thanks, i was afraid of that. Having 2 crossbows and managing them separately will be an issue as they upgrade. However, this does offer a work around.

Happy to help, wish I could have delivered better news.

You could also make it Versatile with some sort of explanation in the text. It will increase the damage on the character sheet by one die class.

Quote from Wysperra >>

You could also make it Versatile with some sort of explanation in the text. It will increase the damage on the character sheet by one die class.

 
They would have to add the Versatile property to each individual crossbow the player uses in the homebrewer.

Couldn't they just add a flat +2 damage to all weapons? If you're going XbowXpert then you'll only ever use a Xbow anyway.

Quote from Agilemind >>

Couldn't they just add a flat +2 damage to all weapons? If you're going XbowXpert then you'll only ever use a Xbow anyway.

 
Theoretically

Quote from IamSposta >>

Quote from Wysperra >>

You could also make it Versatile with some sort of explanation in the text. It will increase the damage on the character sheet by one die class.

 
They would have to add the Versatile property to each individual crossbow the player uses in the homebrewer.

 I was thinking making the bracers with a base of crossbow and call it bracers. I suppose that could get confusing.

Quote from Agilemind >>

Couldn't they just add a flat +2 damage to all weapons? If you're going XbowXpert then you'll only ever use a Xbow anyway.

 Would that modifier work on melee attacks?