fire,ice,lightning damage on weapons

I know this has been mentioned before because I used the search, but no one ever comes up with an answer at all.. I want to know why I would use a fire damage hammer over a normal hammer.. other than the fact i can kill ice elementals easier. I remember hearing a rumor that lightning damage penetrates armor to some extent. is this true? what do these elemental damages do pvp wise? thanks for help in advance.

Lightning damage on weapons does not penetrate armor. I use a couple of different elemental hammers plus a physical hammer. Why, because if I see my attacks are being resisted, then I can simply switch to a different type and try to do more damage. Players armor has various modifiers to elemental resistances, and physical for that matter, so if Im fighting another warrior, I dont want to use my physical hammer. If Im fighting an elementalist, using fire (or cold or earth) may not be a good idea. There is no HUGE reason to use elemental damage, its useful though if you want to maximize damage potential. Hope this helps.