Fill in for Christianity similar to The Seven in ASOIAF. Symbolism uses a point down sword? Similar to cross. Maybe connects to the sword in the stone? Faith plays up reverence for martyrs (Hence the name) rather than saints. Not sure how to incorporate Grail.

The gist is that there’s a Jewish like religion that is ethnically connected. The First Martyr combines aspects of Jesus and Paul and basically preaches that Gentiles can be accepted as well. The “Jewish” leaders opt to stonewall him. Followers on both sides are getting increasingly rowdy. The Roman equivalents get afraid that this is going to boil over from a cold war into a hot war inside their territory and opt to have the Martyr assassinated, paying a traitorous disciple to poison him. Unknown to the traitor since he was off getting his 30 pieces of silver, the Martyr had gone to the temple earlier that day and symbolically gave up arms and urged his followers to peace, driving his sword into the stone in front of the door (stealing a bit of Martin Luther nod as well). The traitor then poisons him that night at dinner. So that way, the grail can have similar importance and the sword (in the stone) can then connect to Arthur! Plus there’s still a traitorous disciple and such. And hopefully make it neutral enough to not offend real world people.

??? - This mid-spring holiday honors an important historical figure. It is marked with ritual purification, an item hunt, and singing.