I mentioned earlier a Heart player that could summon a manifestation of their spirit Which heart player do you think would fit the bill of giving other players the ability to summon spirits of their own? Apart from having its summoner's senses and being able to touch stuff, each player's spirit could act as a focus for their powers. This could, in turn, probably act as a way to help said players unlock their powers.
I think rather than letting other players Summon their own Spirits, it would be the same Maid or Sylph summoning others’ copies by themselves, but otherwise, perhaps a Knight or Page since they’d ‘Serve’ their Aspect? Hmmmm…