Strange stats on this gold axe.

Furious war axe of warding
Slashing Damage 6-28
Damage +13%
Armour -10 (while attacking)
Double aderenaline on hit (chance 6%)
Armor +6 vs. (Elemental damage)

Would anyone seriously buy a weapon with this negative armor statistic? There is a permanent 13% damage boost.

What is this weapon worth?

yep, the negative stat is really bad.

No, it's not. It's the best negative stat there is. -5 energy? No thanks, the warrior is already an energy deprived class. -health regen? Big no no. -energy regen? Possibly worse than -5 energy.
-10 armor while attacking? Sure. In PvP it's not like a warrior is going to need that extra 10 armor while attacking anyways. They are almost always targetted last.