Blessing of Silvanus provides a +2 critical threat range bonus to mauls which AFAIK stacks with every other crit range bonus. That plus bonuses to Favored Weapons (e.g., Ascendency) is what has historically given e.g. PDK Silvanus paladin 20 an edge over other maul users:
- 20/x3 base
- 18-20/x3 Blessing of Silvanus
- 17-20/x3 Improved Critical feat
- 16-20/x4 Holy Sword
- 16-18/x4 19-20/x5 Overwhelming Critical
"Axiom of Faith: Multiselector: Choose a Religion from the full list of Religions. You are now considered to be a follower of that religion, including being able to use its Favored Weapon."
IIUC this would make a non-Silvanus paladin able to benefit from Favored Weapon bonuses in the KotC tree, however they don't gain other religion feats like Blessing of Silvanus. But I don't have any level 23+ paladins I could use to test that at the moment.