Armor Repairs...
Each time you die (not go downed) you damage a piece of armor. When all your armor is damaged (eight pieces including your back piece and aqua breather), the next time you die a piece of armor breaks. That means it ceased to give you the protection and stats on it..and it actually disappeared, until you repair.
You can not damage armor from falling damage, but if you fall into something like lava, and die in the lava you can.
I don’t know about the vengence warrior skill though. Hope this helps.
This may answer your questions: http://wiki.guildwars2.com/wiki/Armor#Repair http://wiki.guildwars2.com/wiki/Repair