You do not need this knowledge to get the 4 energy. I just completed everything in the "Sherekhan and the Crimson Dragon's Adventure Journal", aside from this knowledge, and unlocked the full 4 energy. Don't know precisely which knowledge entries in that section you can skip, but this one you can.
Você precisa do coração de Garmoth mais 4 de energia. Só conversar com o ferreiro de Duvencrune (Hugol). O mesmo NPC que te dá as quests diárias para fazer a Dragon Slayer. https://imgur.com/Aue5Uq0