I agree, but I could see her 'accepting' Piper's offer. After all unspoken assumptions are not legally binding agreements and this is business, not something between friends. If she thinks that selling something for an honest price is enough to get a favor out of Pyrrha Nikos (who is probably somewhat used to people offering these favors freely as a way to curry influence) then more the fool is she.
You don't understand how these thing work, do you?
1. Phyrra won't accept that kind of slimy line of arguement, because her pride, I mean just see the the 'refuse' option, where there is invisi text to underline just how much it goes against her pride
2. Even if you some manage tp break the deal, breaking these 'unspoken assumptions' is a good way to ruin her reputation, I mean you don't want to do the favor sure, go ahead and be my guest, but don't expect people ever offering stuff like that again if you do once you have proven untrustworthy in regards to these things
I mean honestly,
The way I can see Phyrra breaking the deal would be if Piper would ask something that insults Phyrras pride more then breaking the deal would do, anything else I find rather unlikely given Phyrras character
Anyway,
In regards to the leadership issue which were raised by Weiss during the chapter, I suggest to get Jaune as our leader, like in canon, because with him being a Jeanne D'Arc expy, his leadership skill will probably be off the charts when shit gets real, and his people-skills will probably also be pretty good,
Well either him or Nora, who should also be a really good leader, as long as we channel our inner vikings as a Thor expy
Also who else was surprised that Blake is a shrine maiden here?
I mean, given the whole mythical gimmic going on, I totally expected her to be more like Belle from the Beauty and the Beast, and not a japanese priestress