Why does this matter? It's a incendiary weapon, not a waterjet cutter.
Keeping the plate in place during combat use is probably not going to work in terms of action economy. You have to draw the plate, draw the seal, place it on the plate, and activate the seal in one round. I'm unsure exactly what the action economy of that is, but I'd guess that's 2 Standards and a Supplemental. Which is not possible. Even if it's one Standard and 2 Supplemental, that means no Sub, which is very bad.
I'd say you're better off giving up on the reloadability of the seal and aiming for a Taijutsu attack with a +6 bonus and Weapon:2 or 3.