1) Tenka Fubu's effect goes up the higher divnity/mystery is, doing the most damage to stuff like Medusa... and doubly so if she's as a Rider because it stacks with her general anti-Rider shenanigans. Gil and Heracles would probably pump it up super high.

2) Papiyas is super rare and won't come out unless things get really bad that she needs it since it's stupidly draining. As rare as regular nerfed Saber breaking out Excalibur in FSN.

3) And she has 3000 matchlocks in stock but without using Three Thousand Worlds she can only materialize three at a time and they're all single shot. Other people can probably use them though since her thing is based around armies and she has both Charisma and Tactics B.