Newbish question

[thejeff]

You use a Hammer whenever you want to forge something. Give it to the mage doing the forging, put it back in the lab next turn (or use it to forge something else.)

If I'm understanding your question properly, you can give any path booster to any mage with at least one level in that path and it will work. (As long as you can give it too him, that is he has the proper slots open.) A Thistle Mace works just as well going from N9 to N10 as from N1 to N2.