Given that UF-Gryphon has seen the Jei blades used by the twins over in SotS (and presumably handled one for himself), I don't see why he couldn't attempt to create something similar here if he really had to.
However, I also don't see why he'd go about putting extremely dangerous weapons into the hands of those who AREN'T trained to use them, which is most witches. (Mio could probably handle one, but not, say, Minna.)