Does it seem reasonable that a collection of superior and legendary welded mithril long swords and battle axes (and a couple bifrost ones) can't decapitate a grimeling or a blizzard man? I gave my military of 8 dwarves all with some variant of those weapons about three months to wail on these things (and they barely even got skillups) and they didn't manage to accomplish it. I had to just reload at an earlier save when I didn't summon the creatures because otherwise I was going to have to rotate and dedicate dwarves indefinitely to keeping them down.
They seemed to decapitate the Balrog and his friends quickly enough, though!
edit: I ask this here because, despite it being well known that a BM is a pretty hard monster to kill, it seems you should be able to defeat it with a couple axedwarves using even steel or iron axes - but I didn't have anyone equipped with steel, and am wondering more if maybe that's just a problem with mithril and bifrost (though I don't understand why it should be)