It's about time these 2 runes are merged into one imo. Usually someone has one or the other, barely anyone actually wears both. It's completely redundant having them on two separate runes. There's a Greater Fervor rune (which is stun & stifle) that is barely attainable, considering it drops from PQ's, which no one does anymore. Not to mention how rare they are anyway. This is also coming from a Cleric who has stifle immunity. Let's make it less annoying for other priests. Or just give every priest steadfast!
What Ainaree suggested is probably more convenient. As long as you can purchase it with a reasonable currency and not the shards of whatever you get from PQ's, because then we're back to the original problem.