I'm still exploring them. I haven't unlocked the magical equipment yet, but I have the mistland bow (and fogsword), I carry around 100 wooden, 100 ice and 100 carapace/mosquito needle arrows.

The point is not that the Soldiers are strong: the point is that it is not necessary to fight everything in my path. Very often it is better to outflank an enemy than to confront him.
This was the case in previous biomes as well.
In the Mistlands it is simply more pronounced.
Someone said that once you use the Bonemass bonus you go back to base to wait for the cooldown. Sure having it ready all the time is useful, but I also can't use it EVERY time I collide with an enemy. I do it only and exclusively if I see that I'm in serious trouble, if I've already drunk my healing potion and it's on cooldown or I don't have any others, if my stamina is really low... then I use the buff as a lifesaver. Not as a basis for combat.
Soldiers just aim for the tail and the crit is almost automatic, plus with frozen arrows you slow it down almost to a stop.
They are powerful enemies.
They -must- be fearsome.
-You have to- ask yourself -every time- if it's worth fighting or bypassing.
This is the actual endgame, monsters have to be scary, tough and powerful.
I would have been very disappointed otherwise.