Ysaac’s left hand is an arcano-mechanical prosthetic.

A specially built base for the prosthetic is grafted onto the stump where his hand used to be. Most of the frame is solid steel, acting as a support system for the weight of the metal limb.
A standardized copper disc engraved with complex runes and a small, polished piece of quartz resting within the center carries the enchantment that allows the device to function. It not only interprets information from his nervous system but also draws upon a small portion of this physical stamina to power the device affixed to it.

Having artificial limbs comes with a number of complications, some of which are minor day-to-day annoyances while others can be life-threatening if ignored.

Maintenance: Due to the constant risk of damage and mechanical failures mechanical prosthetics require daily maintenance and care.

Cold Weather: The steel frame of most prosthetics conduct heat easily and as a result present an incredibly high risk for frostbite at the grafting site in colder climates.

Swimming: The weight of even a single mechanical prosthetic can make swimming difficult and potentially dangerous.

Anti-Magic: Because the prosthetic relies on an enchantment to function, it will go limp while under the effects that nullify magic, such as Antimagic Field.