These would match along perfectly with my previous gnome rants on the custommagic subreddit. (TL;DR: Gnomes should be UR Artifact lover humanoids, not literally potion-esque artifacts)
Creature - Gnome Artificer (Common)
T: Add 1 to your mana pool. Spend this mana only to cast artifact spells or activate abilities of artifacts.
I have also done a similar artifact exploit effect for the gnomes. I've slightly reworded it to allow for it to be a keyword. Perhaps Scrap is the wording we are looking for?
Creature - Gnome Artificer (Uncommon)
Scrap (When this creature enters the battlefield, you may sacrifice an artifact)
When Gnomish Rocketeer scraps an artifact, Gnomish Rocketeer gains +4/+4 and gains flying until end of turn.
you guys are right that it could be reflavored to be more spiritual. in fact, i was just looking through my personal list of abilities and i had had created back in February the same ability with a different name and flavor (it was in response to someone else's Orzhov thread). these were my notes and example:
Possess sounds like it should modify the other creature. which leads me to make an Aura version of this (kind of reverse bestow)
Beneficent Soul 3W
Creature - Spirit
Possess 4W(You may cast this as an Aura enchantment spell with enchant creature from your graveyard for its possess cost. If this would leave the battlefield, exile it instead.)
Enchanted creature gets +2/+2 and has flying.
this version does have the exile clause.
however Possess might be too narrow in flavor. maybe call it Embody.