Are you suggesting different factors affect dagger damage (ignoring it actually saying backstab critical)?
When it registers a backstab hit it says Backstab Critical. Comparing to an even levelled 1h I am doing far less damage per hit, and obviously way below the 2h. (by far less, I mean each individual strike from the dagger is around 20% of the 1h club the other hero is using, culminating in a horribly low amount of damage output)