When enhancing, collect about 25,000 souls. The number next to the soul meter should say 25. Enhance all of your weapons and Orbs to level two. After collecting the Wind Orb, use the remaining souls to bring that to level three, since it is weak.

Save your green and red mana for the fourth sword. It can be found just beyond the destroyed master's house (level four or five). By saving points, you can build the weapon up to full immediately.