What the heck are these ?

[Sudsy]

Various sizes
Like hand drills with post guides
Maybe for flattening the bottom of a countersink hole ??

[Bill Houghton]

They're counterbores - think "countersink," but with flat bottoms to the hole.  I've never seen a hand-powered one, though; must be intended for pretty soft wood or other soft material.

Or they're something else entirely...

[Yadda]

Maybe a specialty security driver set?

[Sudsy]

must be intended for pretty soft wood or other soft material.

You can see where they've been hardened at the tips. I doubt you'd do that for soft woods

[Bill Houghton]

Looking at them again, I'm mystified.  The counterbore part doesn't look sharp at all - either they're worn down, or I'm misinterpreting what they're for.

And the pilot (center part that sticks out), which does, indeed, look either hardened or "burned," doesn't drill a hole; it goes into an existing hole.

[lptools]

Hello, Sudsy. Mabe a de-burring tool for a counterbored hole?