Hot water faucet handle stripped
There are manufactured solutions for your problem that will work way better than glue/epoxy or a bunch of work with saws and stuff.

Use a "fit-all" handle arbor that attaches to the stripped stem with set-screws. There are dozens of handle styles to choose from.

Will it prevent you from having to find a replacement stem or replace the whole faucet? YES

Will it work way better than other options and still be aesthetically pleasing? YES

Is it simple and easy and quick and relatively inexpensive? YES

Will you need to change both of your existing handles/knobs? YES