PC on Fire Prism of Swiftness

I want to know the value on this item I found in a chest today.

Skinn:


Stats:


Fire Prism of Swiftness (Gold)

Energy + 12 (Requires 9 Fire Magic)
Halves casting time of spells (chance:10%)
Incsription:"Hail to the king"
Armor +5 (while health is above 50%)

Thx, for helping .

Bump, bump, bump.