I have to mirror what others have said.
I think that the Arkentools have no innate power themselves. I believe that is why its so important that they "attune". This process aligns the tool to its chosen user. Wanda is the easiest to see in that regard because she is a MAJOR croakamancer. But what about Stanley? He's just a pikeman right? Well...no....not assuming he DID become a leader through regicide. He also must have had a very powerful innate ability to control monsters in order to get the gobwins to serve his needs so well. Twolls too....can't forget those. Spidews...the list goes on. Stanley already HAD a very powerful ability to lead and dominate monster type units. The hammer just jacked that up, a ton. Giving him dwagons (which we are lead to believe are pretty much the end all be all monster unit) and the ability to use powers that the monsters he controls can use, such as flight and lightening and fire cones.
Now, you may ask, "Then why did the pliers so specifically target undead before wanda had them?" I could theorize all day about that. Maybe they only did so due to whom was wielding it...and their close proximity to Wanda as a result. We are given no other examples of uncroaked units that Ansom has faced outside of Wandas...but we ARE told that they have fought many battles against Stanley and Wanda already. I would feel safe assuming that its likely Ansoms first real foe while having the pliers was Wanda (given that she tells us he became her focus immediately after realizing Stanley would not lose to Faq and that Ansom had them)...and her main force is uncroaked anyway. Perhaps upon coming that close to a unit they COULD attune to...the pliers began to attune in small ways to that magic.
I'd assume, as well, that croakamancers have spells to straight END uncroaked units. It would come as no surprise that the pliers, after coming close to wanda and beginning to attune, would take on traits that worked with that magic. If it had been Sizemore that the Pliers attuned to first, I suspect Ansom would be smashing golems in a single blow. It all adds up for me, and it suggests that the artifacts are not naturally set into certain fields of magic...but take on the very traits of the ones they attune to. That answer, to me, is far more understandable and fitting for the story. My only deviance from that is the Arkendish...since it, thematically, could only really make sense as a projection device. Then again, maybe the items, upon the death or loss of their previous attunement, immediately pick a new target for attunement and change themselves to suit it.
Perhaps the Dish may become an Arkenshovel...so to speak, should Charlie ever die. Perhaps they are only ever meant to attune once, and change based on the focus choices of their target. Perhaps they, much like Hamster, aren't a natural part of Erf, and follow whatever rules the "Dungeon Master" running this game chooses. It may very well be that this IS literally a game, and not just a messed up dimension, and there are literal players. It may be found one day that Parson merely perceives the game as an actual world, because of how he currently relates to it. Who knows?
I do think that the tools themselves are merely amplifiers and extensions of the ones they attune to. So far as I've seen...it not only fits, but is constantly proven every time we read more.