Thomas experienced all the pain he inflicted on others when he was sent down, which suggests a redemption arc.
However the little scene explaining the swords, doesn’t just explain the sword of faith, it explains them all, and if they powered by an angel then, it suggests all are capable of a range of effects if one intercedes with the angel. Killing his hunger at this time will kill Thomas, he needs massive infusions of life energy or a suitable alternative.
Thomas is susceptible to True Love as a white Court vampire, and Harry has the sword of love, The Shroud and the Crown of Thorns, so what if instead they are used to invert Thomas’ demon from an incubus to an outcubus, a Cupid, feeding on love freely given, and repulsed by naked lust. Love is akin to the power of creation, Lara gets her brother back but radically changed, Harry retains a powerful ally, Eb gets a cupid as a grandson. Eb is actually quite speciest, not just about Vamps, but see how he treats Etri’s people, he might still have problems with a new Thomas and with Bonny.
This would allow Thomas to pick up a sword and be Arthur to Harry’s Merlin.
We don’t know enough about the White Courts origins, what if their founder was someone like Cupid corrupted? And Harry can correct it.