On the unarmed weapon list, Wiki says that the spiked knuckles DMG is 8 - 20, on Spiked Knuckles page it's 11-25, but in-game it seems to be different from both - 8 - 22 (at least i thing so, 17 bunus mellee, displayed dmg in inventory 25-39, there aren't any extra modifyers i know of)