My oldest character, Rock, on Baja, was built to have a similar role. Since I wanted him to fight, too, the template varies somewhat from what you propose:
110: Mace, Music, Peacemaking
100: Healing, Anatomy, Tactics
50: Chivalry
40: Focus
Since Chivalry is mainly there for Sacred Journey, I've been thinking of dropping it and Focus, and go with a 6x legendary build. He'd use charged runebooks and/or runic atlases to get about. If you don't have a scribe, Recall scrolls can be bought in many mage shops. (Some sell level 4 scrolls, some do not.)
Your template has Magery without Eval Int, making it quite weak, useful mainly for Recall and, if you put enough points into it, Gate. At least one spell, Bless, is completely uncastable sans Eval. If the character were human, he would have 20 Eval as part of his Jack of All Trades. I believe this is enough to cast Bless, but only buffing your stats for like 1 point each, with a duration of about 3 seconds. I don't know how good Greater Heal would be, but I wouldn't depend on his magical healing or curing capabilities.
If you were willing to drop Magery and Discord, and depend on charged runebooks for travel, you could buff your healing/restorative capabilities a lot, and give yourself some useful offense. Mysticism includes the Cleansing Winds spell, which is a small area AoE (area of effect, simultaneously helping several close characters) that heals, cures, and removes curses. Yes, you can target self with it, or your Sampire. Additionally it would offer some debuffs, direct damage spells, and arguably the most powerful summoned pet, Rising Colossus. If you went 6x, the template could look like:
120: Mysticism, Focus
120: Music, Peacemaking
120: Healing, Anatomy
(or 100 in Healing and Anatomy, with 40 in Hiding)
Note that Focus is one of two buff skills for Mysticism, like Eval is for Magery. (Its other possible buff skill is Imbuing; their effect is not additive, though). Focus won't be sufficient mana regen (MR) on its own, so your armor and jewelry should include MR, reduce mana cost (RMC), and, likely, lower reagent cost (LRC). One of Mysticism's mastery skills is Mystic Weapon, which is a castable form of Mage Weapon but for Mysticism. I think it lasts 10 minutes, at which point you could cast it again. Even if you don't plan on melee fighting (or archery), wielding such a weapon would provide you with protection against being hit. Since the build lacks Tactics, the warrior equivalent of Eval, you shouldn't be depending on the weapon for damaging foes; it would mainly be defensive. (However, having high Anatomy does assist weapon damage significantly, as well as buffing the damage of your Mysticism summon, Animated Weapon. Since AW also depends on Tactics, it won't be at full power, but at least it won't be totally nerfed.)
I'm not saying Discord is a bad option; I think your Sampire would appreciate how it can partially nerf most foes. And unlike Peacemaking, its duration is unlimited if you stay in sight of the foe. If you go that route, your build would need neither Focus nor Meditation. In that event you could build Hiding skill to full power. I guess it is a matter of which you think will be better for your Sampire, one very powerful debuff skill plus Hiding, or a large toolkit of good spells.