@DANDAN_THE_DANDAN I'm guessing you've never witnessed any live explosives going off (not expected of a civilian, after all). Most of the damage from grenades comes from the shearing forces of shrapnel, not the explosion itself (any one who has handled grenades and other types of explosives during military drills would know about this).
Any metal plate in that room (like the underside of the classroom desks) which is thrown at high enough velocity will cut flesh and bones in half, no problem. A body vest full of dynamite is definitely "enough velocity"--just as a rough rule of thumb, a single candle of dynamite [75% NG + 23% Kieselgur] like the one in this comic has about the same amount of explosives as a standard US military issue M67 hand grenade [91% RDX] would contain--dynamite has a detonation velocity of approximately 7500m/s, more than fast enough to drive a metal plate clean through any organic material. How's
that for shearing your suspension of disbelief out of the water (pun intended)?
That said, I doubt the author is an ex-military explosives expert with this kind of knowledge off hand, so I'll hand it to you--it was likely just convenient theatrics for
explosive effect.
