I remember the army teaching me about the dangers of blanks, in fact we were lectured about it frequently. We were taught never to fire blanks at people at close range, especially so their faces.

Right, I never did that, but yours truly had to experiment anyway so at an inconspicuous moment I fired at point blank range into a large tree and I was showered with bark fragments which cut me quite badly. In hindsight, if the bark had hit my eyes I might have been blinded.

The wading that stops the charge from leaking out is actually quite substantial and it's this rather than the hot gasses that do the damage.