Tom Del Rosso wrote:
I just twisted a torx bit into a spiral trying to remove a rusted screw,
then used a Dremel to cut a slot across the top and took it out with a
flat screwdriver. The screwdriver didn't bend at all.

None of the bits I ever saw are made of hardened steel like a
single-piece screwdriver. Does anybody make harder bits?

Snap-On and Proto both make good torx bits. $12 per bit.
They don't bend, they just suddenly break.