Bleeding dmg goes through 'all' defenses (armor and magic resist/protective barriers) and is only affected by difficulty or the immunity of some enemys (i.e. Automatons). Orkish axe-weapons are bugged and will do significantly more dmg than weapons made of any other material. Dragonbone weapons are bugged too, they miss the related tag and wont do any bleed dmg.
You can stack bleeding dmg an unlimited number of times, so an orkish one-handed axe, augmented by Elemental Fury will do the most bleeding dmg possible. You can spice this up with the Targe of the Blooded (shield).
For further informations, be sure to check James' discussion about how bleeding dmg works (in detail):
http://tamrielvault.com/group/glitches/forum/topics/how-bleeding-da...