Thank you for that photo. I tried to find one.
The Dai is like the Korean car Hyundai ending. That was my first thought.
But the sai martial arts weapon is a similar word, or this one, too:
The daishō (大小, daishō)—”big-little”—is a Japanese term for a matched pair of traditionally made Japanese swords (nihonto) worn by the samurai class in feudal Japan.
Probably this 戴, or more likely the Chicom simplified version 代.
But it’s impossible to know for certain from just Dai.