Hi jimi - Ok:

All barrows has a "Special Attack Bonus"

Guthans : Restores health with the special attack on the spear (The special attack is totally random, theres no spec bar)

Torags : Best defence on the game.

Veracs : With the FULL set including the Veracs flail, you can hit through any prayer.

Karils : Kind of a waste of time, the bow hits very good.

Dharock : Will full dharocks you can hit up too 82 (Must only be wearing dharocks, and any other str bonus items) - This of corse depends on your defence level.

I hope this helpes you make that all important Barrows question!