think of it he has the crossbow and give him a suit just like Desmond Miles, and so forth. and it can be a skin like with slightly different animations like he can shoot the cross bow from his wrist, throw the cask like how he would throw them, etc.

Xbow on a wrist - Vayne.
Cool cape with hood - Talon.
Also there's medieval twitch skin if you didn't know already.

I feel like Talon would be a better fit for AC skins.

As cool as it would be, unless Ubisoft's ok with it, this could be a bad idea.

Don't need Ubisoft's permission as long as it is not an exact copy, or using the name "Assassin's Creed" or any other copyrighted/trademarked/etc., name/title.

Hell, in D3 there's a legendary DH cloak called "Beckon Sail", with the description "For those who travel in the underworld." It totally looks like Selene's Death Dealer armor. There's another one called "Cape of the Dark Night" that I've been looking to get my hands on.

Moral of the story, heavy referencing is perfectly acceptable.