That’s easy, it has been enhanced with horned.
It’s exceptional crafted so normally I think 36 resist with armslore, that has total 51, and horned gives the 15 resist difference.
But you know, you won’t lose a charge or anything if you try to enhance a piece that has already been enhanced. You can attempt it with a forged tool then you can even put the charge back on the forged tool by using the tool a second time.
it’s only when a piece is on a vendor/auction safe that the issue requires a veteran player’s knowledge.