PC on Near perfect storm bow

Bought this unided for 28k
Am I looking at a gain or a loss here?
How much does that 14% kill the price?

Poisonous Storm Bow of Warding
Piercing Dmg: 15-28 (req.8 Marksmanship)
Dmg+14% grrr... (while health is above 50%) woo!
Lengthens Poison duration on foes by 33%
Armor +7 (vs. elemental attacks)

around 25k