Inhuman creatures in the Dresden Files may know more or be more powerful than humans, but they are not inherently stronger willed.
I think that applies only to people that were once human and/or are still close to human and think, more or less, like humans do. A single "Lord of the Outer Night" would be mentally strong enough to overwhelm a wizard through application of will alone, as Odin cautions Harry. And Bob is so mentally powerful that he can resist several of them combined.
And that's before going to things like angels or outsiders.
I think that applies only to people that were once human and/or are still close to human and think, more or less, like humans do. A single "Lord of the Outer Night" would be mentally strong enough to overwhelm a wizard through application of will alone, as Odin cautions Harry. And Bob is so mentally powerful that he can resist several of them combined.
And that's before going to things like angels or outsiders.
Yes. But isn't that reflected through skill? That has nothing to do with mental toughness. It's just that they are able to deal tons of mental stress if they want to. Possibly through a very high conviction skill or an other power. Toughness has nothing to do with it in my opinion.
As he has no touchable physical form I'd treat Bob's mental stress track as his physical and vise versa. He has no physical stress track so to speak. His ability of shielding someone from mental attacks is a customary power that spirits of intellect posses if you ask me.
EDIT: Ah damn ... DMW was faster ... again ^_^