The weapon is too cheap and (IMO) shouldn't really be used with shields, but I like it that there are some daggers with strong stats. I wish there were some stronger daggers and then make it so that they can't be used well (or at all) with a shield. Other than that, I feel that there are enough counters built into the game to stop it. People who built slow characters will just have to be wary. 17-7 also isn't very convincing, you're a glass cannon that can get quick hits on enemies, but also die easily once caught.
With around 200 wpf and hardly any armor, it's like adding +2 to +3 PS compared to your average build. With low PS, it doesn't matter much since you only get ~16-32% extra damage. Your 0PS is easily mitigated by high base pierce damage, high wpf, and speed bonus (easy to get with stabs since moving forward is the optimal movement). Even so, I doubt you'll 2shot people from full health if they don't let you get those high bonus attacks + holding; it's their fault for not having enough ath/too much armor and must accept this (rare) weakness. My 8ath guy would have a much easier time and can still wear better armor.