I'd personally say MPII doesn't feature enough army summoners! Yeah, it's got all the big names like Napoleon's Grande Armee, Caesar's Legions and Genghis Khan's Mongol Horde, but where's the real hardcore stuff like:
* Qin Shi Huangdi's Terracotta Army,
* The aforementioned Skuld's army of viking zombies,
* Lleu Llaw Gyffes[1] leading trees to battle at Cad Goddeu,
* Pachacuti's army of the earth itself,
* Solomon's army of djinni, angels and demons... hold on,Spoiler:
Anyhow, I've been giving some sort to an actual Servant Guinevere sheet, particularly after reading these articles. My other thoughts were Lancer/Rider Europa (would be pretty high-level either way, though as Lancer she'd be a bit similar to Prokris NP-wise), Lancer/Saber Mohini (the sole female avatar of Vishnu, would be most suited to the Temptress class but that's of dubious existence) or Archer Marie Antoinette (she participated in hunting, which she'd have likely used a bow or gun in).
[1]I'm aware he's commonly listed as a god, but an RP site that's usually pretty strict about this sort of thing allowed him fine.