What built in mechanics does DnD have that track sense of self?
Why do you need a rule book to tell you how to do that? Anyways that is pretty much reflected in your Cha score, when it hits 0 you become a potato without a sense of self. Damage to Wis also does this, and outsiders like Gibbering Mouthers (aka lovecraftian horrors) do this.
What mechanics encourage the use of a completely non-combat capable character?
That depends entirely on the campaign you are playing. You can do the same sort of emo intrigue wankery that is the ONLY thing you can do in VtM just as easily in DnD. You just have to have a group willing to do that. After all, most of the spells in the 3.5 handbook are non-combat spells. Zone of Truth does nothing in combat, Sending does nothing in combat, Stone to Mud does very little in combat. For that matter most of the skills in DnD are non combat.
Why do you need a rule book to tell you how to do that? Anyways that is pretty much reflected in your Cha score, when it hits 0 you become a potato without a sense of self. Damage to Wis also does this, and outsiders like Gibbering Mouthers (aka lovecraftian horrors) do this.
That depends entirely on the campaign you are playing. You can do the same sort of emo intrigue wankery that is the ONLY thing you can do in VtM just as easily in DnD. You just have to have a group willing to do that. After all, most of the spells in the 3.5 handbook are non-combat spells. Zone of Truth does nothing in combat, Sending does nothing in combat, Stone to Mud does very little in combat. For that matter most of the skills in DnD are non combat.