[quote=@Artifact]
<Snipped quote by souleaterfan320>

How much is enough?
[/quote]

Roughly 1 percent. The exact ammount that is in each knife. Even if you took all 20 knives and busted them into shrapnel or melted them down to use in a bomb, it would disperse to a point where that overall percentage within the blast area could be less, possibly significantly so.