Backup PC in development...

Meant to replace the party's cleric, this Paladin shares the same faith, and his church would (cough) request that he be allowed to take his place... mainly so that their interests are still observed in the group.

Gideon [LASTNAME] is a citizen of the nation for which the team functions as operatives. He is a survivor of a recent-ish war, one that his nation technically lost. He was part of a unit that suffered particularly heavy casualties. He lost his left arm, which is currently replaced by an arcane-powered prosthetic.

It's not all he lost in the war, though: His wife and daughter were slain in the conflict, innocent victims of errant artillery strikes. In his anguish over their loss, he sought solace in religion, and eventually became a holy knight of their cause.

Magical prosthetics

Conveniently, it's already a thing in D&D... the "Prosthetic Limb" is a common magical item from Tasha's!