When exactly does the OnHit event fire?

[Surgo]

I wanted to create a stupid little mod that would make daggers more effective as assassin weapons, rather than just being pointlessly fast to swing. So I wanted to make poison 1.5x as effective when it's applied with a dagger. Okay, simple enough concept. Figure I'll just register an OnHit handler that checks if the item's a dagger (well, that check is fairly complicated, but you get the point) and if it's poisoned and, if it is, makes the poison 1.5x as effective.

 

But the question that raises -- when OnHit fires, has the poison already taken effect, or are we still before that point? Because if it's already taken effect, then this is simply no good.