Yeah, this can be a fairly tough battle. As said above, don't bother trying to actually destroy the boneblades, just try to keep their attention away from your party. Morden's Swords are truly wonderful here, but any good summoned monster will do. Have your mage(s) be ready to breech any protections that the Ravager raises, particularly the globe of blades and stoneskin.

This is a great battle for a tank wielding Foebane. While it doesn't have true regeneration, it's Laroch's Minor Drain is just about as good as regen, particularly in long, drawn out battles. A good tank can get his total HP over 250 in such a battle.

Just remember though, the reason he's hard to beat is not because he does TONS and TONS of damage, its cause he has uber high regeneration. ;x