So, the fix for Not a war hammer achievement is long known, it is to install Dwarfs!? F2P version of the game, get it there, go into Dwarfs!? paid version and in theory you should get it.

However there are instances, and i had it as well, when getting it in f2p version and then going in paid didn't unlock it, if you are one of the people who had this same exact issue. You have come to correct guide.

Fix is as simple as it gets.

Uninstall both Dwarfs!? versions (F2P and paid one).
Install them both again.
Launch Dwarfs!? F2P.
Play untill in-game you see achievement pops, even if you already have it in Steam( on f2p and not on paid version).
The moment you see it unlocked in-game.
Save just to be safe.
Quit game.
Launch Dwarfs!? paid version.
And GGs, achievement should pop.
If it still doesn't pop, repeat these steps.

This should work for any glitched achievement.
Both instances of game use same save file, so when you get the achievement again in either versions, it will pop in other, just be sure to actually launch other instance.

Hoped it helped you, because it sure as hell did for me.