Hyros Bow - any information?

Found this insanely powerful bow at the imperial camp by Dawnstar and I'm wondering if anyone knows anything about it? Can't find any info on it online.

It's called 'Hyros' has a freeze enchantment and on my las playthrough it had 152 damage and this current playthrough I just retrieved it again and it has 600 damage?!

Is it from a mod that I'm running and I'm not aware of it, has anyone else come across this bow?