No, I think the defense starts working after the rage is spent; spending it doesn't affect the defense (I think I read that on Nival's website)...

Added after 4 minutes
It's better to level up luck (magic resistance), and find some boots – it's not that rare of an artifact... and forget about the block and defense, and instead take, say, education or shouts, whatever drops... Although there's a perk in defense called resilience, which at least increases HP... it's debatable...