I can't reapeat it again, so I guess in my case it was random or game bug. But I got over 150% crit chance and over 1000 dmg without any buffs and mobs died 2 hits.
What I was able to check, that this glitch can be removed only by relog. Mount, changing weapon or char's death do not remove glitch.
When I'll back to my place after holidays I will try to look closer and compare screenshots I've made.
edit:
but I think it's matter of time that someone figure it out, if it happened to me while normal playing it could happen to anyone