Viggi's page

I am trying to get my head around how the Staff Nexus works with a new Staff.
1st level my wizard has her first staff:
Cantrip: Ray of Frost
1st Level: Magic missile
To prepare my wizard needs to sacrifice a 1st level spell slot, to give her 1 charge.

Later wizard acquires an Animal Staff
Cantrip: Know Direction
1st Level: Summon Animal, Magic Fang

So, during preparation: sacrifice a 1st level slot gives her 1 charge for original spells.
Automatically gets 1 charge for Animal Staff and can sacrifice another 1st level slot to get another charge.
So she could have 3 charges to cast what off this staff?
1 Charge to only use summon animal?
3 Charges to cast any of the spells?

Guidance appreciated

I may have missed something, and there is always GM fiat, but how does a PC gain access to uncommon weapons with no Race Trait or Region connection? The Unconventional Weaponry Human Ancestry feat doesn't seem to cover the Spiked Chain, Kukri and Sawtooth Sabre. So is it just down to the GM and a good background reason?

I will be starting this in feband have high hopes, will post links to the ongoing story