Remove holy/unholy water’s ability to bless/curse items. Instead, make blessed and cursed oil serve the same functions. Dipping a stack of uncursed oil in holy/unholy oil will bless or curse the stack, as currently works, but since oil is significantly less easy to get than water, this makes mass-blessing of items harder to accomplish.

Anointing an item with holy or unholy oil ignores effects that would normally happen because of the oil. For instance, dipping an oil lamp in holy oil will just bless it, or do nothing if it was blessed already.

Priests now start with a stack of 4 holy oil.

Water doesn’t get outright removed - other things still dilute to it and turn into it in random alchemy - but it’s not much use anymore except for on-the-go dilution.

Not specified whether you could pray to get a stack of oil potions on an altar blessed, or whether this wouldn’t work.