ToME Wiki
Why play a Haftedmaster?
Most people try out haftedmasters so they can use Grond. Grond is perhaps the only sentient artifact weapon you are guaranteed to find in addition to being very powerful in its own right. Obviously, Grond is quite useless if you don't plan on stepping through the Void, since you probably are already using a powerful hafted weapon to take out non-Void monsters.
Another good reason is the skill Stunning-Blows. This skill gives you a percentage chance to stun monsters when you score a critical hit with a weapon over 5lbs. Given the weight of many of the bigger hafted weapons, Critical Hits can happen quite frequently. The only disadvantage is that this skill is quite expensive (only a .500 mod), and limits the degree to which you can diversify your Haftedmaster into other skill areas.