Upgrading your weapons in Dark Souls 2 is done through the blacksmith in Mejula as soon as you find the key to his shop. (The old hag sells his key for 1000 souls in the Forest of Giants). For a small fee and the materials required he will upgrade your weapon anywhere from +1 to +10. No Embers needed. If you are interested in turning your weapon magical or elemental then you must use certain stones to convert your weapon.