"I keep it close as a reminder that even the most evil thing can be purified by the power of light, and find usefulness in service of the righteous."

Roleplay is a tricky thing. As long as you think of it from your characters perspective, there are a thousand ways to look at anything.

I can easily see a sphere Purity character that wouldn't wear them and would judge anyone that did (I've played more than one or two). But I could also see someone another good character that wasn't so strict making use of anything that benefited the good, without placing much stock in pointless decorations.

Nothing inherently wrong with a Good character using those. Nothing wrong with a Maran/Acolyte using them (if they've been purified), as long as it can be explained in an IC way.