If you complete the plotline with getting the vase/dragon stone out of the museum it should be mandatory.how to get shielded charm
1) Charm Mrs. Granger and get her to steal the vase from the museum (requires sending her out to the wild ranges first I believe)
2) You get arrested. Charm the DA + Police Chief if you haven't already
3) Figure out how to charm the security guard (involves possession which requires a lock of her hair)
4) Take the vase and bring it to either Hannah (girl in the mechanics shop in the shopping area) or the Library with Monique. I actually forget which you go to first but one leads to the other
5) You end up learning the shielded charm spell after this.