Thanks Knightmo.
I wish I'd remembered the putty for the armor, instead of using the glue.
What I was worried about--the acrylic paint, even with binding undercoating and sealant, damages easily. So I bet the putty would have torn off paint.
For the naginata, however, the putty proved my last recourse. The glue simply wouldn't hold the blade straight, and I found the putty to be the best option short of making a pin or trying to cut a "male-female" notch in the pole and the blade.
But, yeah, as with your samurai, if this guy takes a dive, he won't be coming back up for air. I'm working on a new armor technique and am tempted to salvage the guy's legs, but I doubt I could even take him apart without completely ruining the paint job (short of sawing off the head to avoid stress-causing Hans-on Method).
-Tim