Not going full force or to full lockout is good advice. I will add that I think “punching with dumbbells” is also an unnecessary risk. Punching with bands might be cool though.
About punching with DB’s. You are right on. Not only a bad risk, but emphasizes incorrect form and distribution of force.
Bands may be interesting, but I’d suggest not doing it. I can’t see a band being too helpful on crosses or hooks…and even uppercuts.
Jabs though, they would probabally work very well.
If you want something for the crosses and hooks and its available, throwing punches under water is a hell of a workout, Marciano did it all the time
Just a thought