Friendly reminder that in Shaolin Monks, one of his fatalities is a straight-up summoning a dozen tiny fire dragons to kill everybody

That’s very possible. Maybe sometimes Kubo gets angry with him, but I feel he would internalize it and remember that his grandfather has no memory of what he did and, like you said, is juts a feeble old man.

I love this moment in the film though when his grandfather asks if he’ll help him remember all the stories he has forgotten. Kubo makes this face briefly:

Then does the right thing.