[K Peculier]

As long as you don't add-on any special effects the weapon would have against Vampires (Aside from killing/ashing them the traditional way) outside of roleplay combat, you're fine to roleplay and note the weapon as a special heirloom.

To note most holy weapons aside from the legendary named-lore ones (Which are unobtainable currently) would be quite effective at ashing vampires, though if they are a player you would still need their consent to permanently killing them off.

As for the topic of the scaled arm, certain races have more affinities with their gods which may influence more pronounced features, as well as some summoner abilities even letting you 'shift' your features into something else to borrow their power. Again this wouldn't really give you any special combat ability outside of displaying your devotion/affinity with a god. You would use the sanctity stat for that in-game which lets you boost your innate Hyattr abilities to be stronger.

I'll allow the scaled arm though this shouldn't evolve into anything further like a full body transformation outside of being a Shapeshifter. Also be prepared to have many characters accuse you of being a Chimera as an IC consequence!

Hyattr are currently in a spot where they don't currently have a clear true 'royalty' line or a specific set of noble houses like you would see from Zerans and Onigans that is currently written up on the forums. Also as they have no real formal empire/official territories you can't really expect other characters to recognize said nobility outside of in-character means, at best you would be described as 'Minor Nobility' which is even an in-game trait we have.

Please let me know if you have any questions or if you need something clarified aside from that!