shadow bow, +15% dmg, energy regen -1 ;Whats it worth?

have a req 12 shadow blade (not axe messed up in title), non inscribable, with a mod that is 15% dmg / energy regen -1, never seen anything like this before anyone know what it is worth?

just merch it................

i would merch, but maby 5kish to a new player.