Holy water

[holypaladin]

While holy water is coming from a christian catholic sacramentalium it didn't got a cross on the bottle but some non-christian akhn instead. To fix that problem I repainted the bottle

[Odium]

I don't think it matters too much whether it's a christian symbol or not. I don't think the religions in Battle for Wesnoth's universe are supposed to really represent real world religions despite some potential similitudes.

The ankh isn't a strictly religious symbol either, from what I can gather it's just an egyptian hieroglyph symbolizing life, which seems to fit the theme.
I think this symbol looks good on this item and doesn't need to change.

[Atreides]

I think it might be useful for some addon that needed it. Wesnoth is a different Universe for sure but some addons are set historically. A crusader addon might find a use for it say.

[gnombat]

The ankh isn't a strictly religious symbol either, from what I can gather it's just an egyptian hieroglyph symbolizing life, which seems to fit the theme.

It is also used in the White Mage sprite.