I'm at work so can't watch the whole thing right now but, in case it's not mentioned in the videos, here's something I just learned that might save others some time.
At the end of all the Luterra quests, when you're getting ready to set sail for another continent, you'll get a series of purple quests that start with King Thirain telling you to talk to his scribe. It's a chain quest that will give you enough uncommon engravings to complete one of your two class engravings. However, it only has 3 nodes so when you equip it, you still haven't activated it. You need 5 nodes to have it active so I was running around like, how do I get more nodes???!!!
Well, it turns out you can equip the same card in both slots, giving you 6 nodes and activating the engraving. LOL! I felt like an idiot! Thought I'd throw it out there to save others the same trouble.