It's an unwritten LAW that You can't do Damage twice with a single Attack.
If the Poison works at the Beginning of the next Round it might be OK ImO
(Well the Part with the injected Poison, not the part with the automatic Damage)
Um, wait, what?
If it's "unwritten", then how can it be a "LAW"?
The whole point of one of these knives is to have an additional effect if the weapon penetrates; I reflected that by requiring a good attack roll (i.e., a critical success), and by requiring it to do actual physical damage. Anything other than these two circumstances could be read to mean that the blade didn't penetrate. Requiring the wielder to wait until their next turn would give the target plenty of time to get that knife out of them, rendering it useless.
And it's not an injected poison, it's not even a toxin at all by the rules -- it's a burst of high-pressure, super-cooled air. It does its damage through sheer pressure, as well as flash-freezing any nearby tissue.
If you want to cite items in the rulebooks that point out why this shouldn't work this way, then by all means do so -- but please include the book (and, hopefully, the page number). If you have a personal issue against the weapon mod, then either don't use it or suggest something else. But please don't quote "unwritten LAWs" when arguing against a proposed house-rule.
Teyl: I'll think about the idea of overcharging a taser, but I'll have to balance it with the general consensus that electricity-based weapons are already
very effective.