From ErfWiki

Proposed Canon

One of the Arkentools. It is currently attuned to Stanley the Tool. It has played a key part in his rise to power.^Erf-b1-p079

Known properties include:

• flight^{Erf-b1-p031Erf-b1-p114}
• summoning and control of dwagons^{Erf-b1-p031Erf-b1-p079}
• controlling lightning^Erf-b1-p113
• turning roughly every fifth walnut cracked with it into a pigeon^Erf-b1-p004
• sometimes turning birds croaked with it into a walnut^Erf-b1-p114

Speculation

It should be noted that some of the pigeons thus created turn back into walnuts after being croaked (or once cooked, or perhaps simply contain walnuts somewhere inside).^Erf-b1-p037 The exact effects of this tool striking living things are mostly unknown. So far in the comic, one Orly has been struck with the Arkenhammer in combat; it happened to turn into a walnut.^Erf-b1-p114

It should be noted that both Thinkamancy (with which the Arkendish is associated^Erf-b1-p104 and Croakamancy (with which the Arkenpliers are apparently associated] lie in the axis of Fate. It was also mentioned that attunement to an Arkentool is governed by Fate magic. ^Erf-b1-p022 So far it is unclear what discipline of Magic powers the Arkenhammer, but it would make perfect sense if that would be one of the Fate disciplines.

Since turning one kind of things into a completely different kind of things is a popular trick of stage magicians it might be possible that Arkenhammer belongs to Stagemancy and Carnymancy in particular.

Real World References

It was pointed out that a company named Stanley manufactures hand tools.