Weapons that Proc..Follow

I have seen people wearing weapons that do lightning damage. I can't remember what level they were, but it seems like they do exist.

There is a quest in Stormhold that gives a weapon that procs. Still got to get the drop to start it though, so haven't seen that weapon myself.

The quest starts from a random, rare drop in StormHold. Rarely, a mob (cavaliers and crusaders confirmed) will drop the Sword of Thunder. Examine it and you get the quest Berik's Revenge.
Kill 100 skeletons, any type seems to work.
Examine the sword again and you will be prompted to kill three named mobs.
Kill Blacksmith Brigg. He is on the top level. Defiled locksmith is his placeholder.
Kill Battlepriest Alexandria. South at atrium. Right at the water. First door on right. Defiled Torrent is the placeholder.
Kill Defiled Lord Byron.

Courtesy of Tentonhammer guild for guide to this quest, but I`ve never seen the weapon myself

There are weapons that proc. Check out the heritage quests and their rewards.

I saw some dagger on an assassin with some proc... gah, wish I could remember. Anyways, they exist, and I'm sure that you'll end up paying a pretty penny for one as well =). Anytime I see them for sell it just says "make offer", so either it's a lot, or they just don't have any earthly idea.

Heritage items with proc effects:
Short Sword of the Ykesha
Electrified Bone Bladed Claymore (You forge Berik, Sword of Thunder with the Bone Bladed Claymore to add the effect from Berik to it.)
Polished Granite Tomahawk

Unsure if it has a proc or not:
Screaming Mace

Heritage that does not have a proc:
Serrated Bone Dirk