I never skip the defense, I just do the whole map (other than post-defense Market Square, of course) before I trigger the defense. Then it's a quick trip to kill the nabasu and maybe the vrock and then grey garrison time.
It's kind of dumb now since you can just walk by Faxon and the demons at the Tower (as long as you trigger the columns) to get the Bow and Armor before Defense, but once Defense is done at lvl 6 it's trivial to hop back to Tower to finish off Faxon and pick up some EXP and items to sell. Post Defense there's no time limit so on higher difficulties I save everything SW of Gwerm until after Defense to do it fully buffed anyway.
You might as well kill him before.
If you chose a good option in shield maze, you get a buff that makes the whole fight much easier. You still need protection from energy to survive fireball (300g).
By the way, storyteller's artifacts shouldn't require resources?
I remember you had to get 5 magic essences at the premiere, now for some time it only requires one, which means you can make the covenant of the inheritor in 1 act.
A similar problem is with other artifacts.