I have a level 81 character and I still haven't encountered a weapon with this enchantment. I've tried revisiting every merchant every 48 hours but still no luck. Does it even exist? :unsure:

Yes it does, I found a Ebony axe with absorb stamina just the other day in a dungeon/tomb...

I think I found one around level 20 in random loot. It wasn't a strong enchantment but it didn't matter as I disenchanted anyway.