Wanda still hasn't worked out all of the Arkenpliers' powers either. She just decided to see if she could use them in uncroaking, because, well, she's a Croakamancer and that's what she knows how to do.
Parson can command dwagons because those dwagons belong to his Overlord and he's a Warlord. Warlords can command any troops belonging to their Overlord.
The Arkenhammer's 'dwagon taming' ability just means 'you can pop dwagons at your capital'.