That’s nice. In a different timeline, maybe they could have just had a great chance at the Holy Grail War and fight until they either die or win the grail.
Except they wouldn’t. She only comes there because of Kirei, and if Kirei summons her there, he catches her off-guard and kills her. There’s no timeline where her and Lancer fight in the Holy Grail War.
But if she was in the war, she might be a formidable opponent, maybe. At first, her attack that forces the opponent to avoid using their Noble Phantasm, combined with her physical abilities, and the fact that Lancer is her Servant, and it seems like she’s got the war in the bag.
But thinking on the Servants of the 5th HGW, there would be quite a few that would be difficult for her. Berserker, maybe Assassin and Caster. Archer too. I do think she would have had a fair shot though.