i got this weapon from the depths, which is honestly a great way to farm actual good enchanted weapons since the depths mainly contains higher tier weapons, so if you do ever find an enchanted weapons, its probably gonna be pretty good.
Note: so from what I understand after some testing, the damage from the m1s are simply just being done over time instead of instantly. So a benefit from this enchant is that your opponent is go to have a hard time attacking back since their attacks will get cancelled due to the damage ticks.