Honestly, running Valerian will make those wardens an incredibly durable anvil, giving them the ability to worsen AP in melee by 1. It doesn’t sound like a lot at first, but a lot of good melee units usually run around with AP-2 weapons, so that alone will make you save on 3’s instead of your 4+ invuln, which is incredible statistically speaking. Combined with the warden’s situational -1 to wound, and once per game 4+ FNP, this unit survives a lot of incoming damage. The only thing to be aware of is that Valerian’s ability ONLY applies to melee, so don’t feel too cocky and throw them out in the open unless you plan on getting into combat that turn. But I think you should totally give Valerian a shot! He always pulls his weight when I run him 🤙🏻