My rule of thumb for power tools is that as long the tool is cool enough to touch, you are safe. I can only take maybe 120 F, so that's really safe.

I don't get too worried about nicks in my axes. As you said, in pretty much all of the old hewn timbers you can how many nicks there were. I've even found timbers that had smooth cuts on most of it, then a nick right after a knot.

I've touched up old straight razors before. That is an art in itself. Nothing like waving 4" of the sharpest thing you'll ever see past your eyes and nose.