You're right - it is hard to fit everything into a thousand words, and I can definitely see you were trying to thread that needle. As for the details of Gnarl's characterization, that makes sense. A simple shift in the language from talking about how his blood fury 'builds' and 'rises' to describing him as 'stoking' or 'building' it (just as suggestions) I think would really help that become clear to the reader.