PC on gold Oni daggers.

ok, IM not sure about these:

(gold) Vampiric Oni Daggers of enchanting
7-17, (req 11 dag mast)
damage + 20% when health is UNDER 50%
Vampiric 3/1
Enchantments last 20% longer


its a little confusing. Im not used to selling daggers, so these definately threw me for a loop.

salvage

for what? what am I tring to get from them? and what will it be worth if i actually get it?