maybe if you looked at DPS? warhammers are very slow....and is it possible that any damage is being placed away in an enchantment rather than in the base damage?

Unless he can hit an enemy over 8 times with a weapon with base damage of 33 in a time period that takes a warhemmer to hit once I doubt it'll top a warhammer of 288 base damage. Even with enchantment, + You can enchant/find a warhammer that absorbs HP as well, in fact you can enchant a warhammer to absorb HP AND do one more thing.
It's true that most artifacts are obsolete after you're an end game character but that's both good and bad, they shouldn't be so powerful that it's the 1st thing people will go after once they start a new character.
Yes, it has a low base damage but it's very powerful. After you've killed 10 people who trust you, it absorbs 30 points of health with each hit. Also, it swings almost as fast as a one handed sword.
Which is not a lot unless you find it earlier in the game.