Should I be able to easily do better? I've got these two niche uniques but I'm rune-poor.
Merc's got +4 all skills Arioc's Needle (non-ethereal), Andariel's Visage (with a Ral rune), and eth +2 all skills arkaine's valor (where need to at least add an Um rune). I have a Call to Arms and make sure to always keep the Battle Command active on him (not just the Battle Orders). I've been running /players3 baals, mostly because I happened to roll both this necro's Worldstone Keep maps with exit tiles adjacent to entrance tiles. (I have Guillaume's Face in cube for him for Baal himself, and my iron golem is made from The Minotaur, so it has Crushing Blow, too.)
The merc's survivability seems good even with his lackluster resists because he takes so few hits with the skeles meatshielding and his high def. I imagine that even if I gave him a Treachery, he wouldn't even end up having Fade proc'd on most runs. I know the conventional wisdom is that merc needs mega damage to create the first corpse for corpse explosion, but these skeles clear the waves quick, man. I'm also tired of running p1, and CE is worth using but not so dramatic past p1.
Should I really make an eth obedience or something else cheap, or am I crazy for thinking this build is pretty ideal? Necro's running 400+MF. I'm short one Ber for Infinity, anyway, but I'm thinking I wouldn't switch for fishyman regardless.

I'd focus on making a pride for your Merc if you want extra kill speed, or a beast for yourself

Alright thanks! I saw Pride and thought "do their attacks really get interrupted that much?"... forgetting that Concentration is just a stackable Might+. I see where the +4 from Arioc's has diminishing returns.

Non eth Ariocs is garbage, and 4 skills on Might Merc isn't gonna make too much of a difference compared to something like Eth Obedience. It's so easy to make too, I'd get one and use that. With Might Merc, Eth Obedience does so much damage.