So this is a series that I read in the late 90's/early 2000's. I remember it as being 4 books.
It involved a boy who, if I can recall correctly, returned to his village that had been burned and his family killed.
He then travels with an old travelling blacksmith/mage who I think was part of a greater guild. I remember the boy forging a sword and while doing so the guy he was travelling with imbued the sword with the 4 runes of the world that would empower magic that was then channelled through it (although this was not found out until later in the series/book).
I think this series ended with the boy fighting his nemesis on a mountain side and discovering the properties of his weapon and using this to end the battle.