Weapon Mod Help

Ok so i just bought myself a shiny new gold storm bow although the stats are'nt too great, its max dam of course a low req and piercing damage (best in my opionn) so i'm happy with that but of course i want to add upgrades at a later date ie. when i can afford them but there are so many mods out there and i'm a little confused about some of them. Here's what i think some of em are.
vampiric= life stealing
fortitude= extra hp
zealous= energy gain on hit?
sundering= armour penetration

I know there's more out there i just can't remember what they are! I already know i want a grip of fortitude, so could someone explain em all to me and tell me whats good whats pointless etc so i know what to look for. Thanks

Give someone a fish and he'll eat for a day, teach him how to fish and he'll eat for a lifetime.

The search button:
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- use key words "item upgrade" or "item modifier" or even "vampiric", "zealous"...
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