Shouldnt this be limited to some specific character builds instead of all?
Surely only the rogues should start or even have this skill-talent for free?
I think it's more that he's limited to what he's able to do with his mod, and without the tools solutions are necessarily cruder. Also, this is a classless system, and making it only applicable to the two presets (Rogue and Shadowblade) would go against Larian's design philosophy of allowing you to change classes (even if that philosophy is not actually practical in game terms.)
Ideally it would only apply to the daggers themselves, but that's a code change.