Battle Afflication

[Taqwus]

Staying in your own dominion and maintaining the global "Gift of Health" will work, but it takes time. Staying in the same province as the Chalice will work faster (seemingly), regardless of local dominion, but that's an artifact.
There's also a high-level nature summon -- the Faerie Court one -- which can help; the Queen can heal others' afflictions, much the same way an Arcosephale priestess can. T'ien Chi also gets a national hero which can heal in that same way. There may be others, I haven't checked 'em all.
Finally, a pretender can heal afflictions when killed and brought back, but that costs magic if the pretender has any left, and in the process of dying may get more afflictions...