Ravidoff:
The power of Giants and the power of Lights encompass diametrically opposed forces. In other words, the two don't play well together. Those who've tried to use the powers together tend to end up, uhm, less than stable... or turn into a raving loony berserker.
Hermuncus anticipated that some heroes who spent many of their resources and efforts toward enhancing these skills should be rewarded with the same opportunity to enhance their new skills. If you had any enchanted skills you should have received some Essence of the Lesser Giants according to the level of the skill during the Awakening process. You can use this to buy Superior Giant's Codexes that you can use to enchant your new skills.