While restoring a sword can make them much better to look at, you can actually damage the value of them (if they have any value and maybe they don't) by wearing away what they call the 'patina' on a historical knife or sword. This was the advice given to me when I had a Franco-Prussian war officer's sabre, which eventually was stolen from me unfortunately.
For example, if it was an SS or SA dagger or Japanese Samurai sword you were angle grinding up I'd be screaming "NOOOO!" at you.
Also, two things. While it sort of seems cool to have sword fights like Errol Flyn, swords are designed to kill people and can do so *very* easily if people are mucking about with them. This made me fearful:
Just think of me as your much older and wiser guardian turkey.I have been wanting to use them to teach my sister how to use a sword, but I'm unsure of how to properly get them up to working order.
Second thing is that swords are likely to be very brittle, so a bit of clang clang is going to mean you have pieces of sword on the ground. Much better to use wooden practice sabers or fencing with all the gear on if you want to muck around sword fight. Also a LOT safer.