The hardest part of this build seems to have been the heat treat. The head first came out in the 55 to low 60 HRC range, which the maker judged too high, so the head was re-tempered down to 50/55 HRC, with another tempering pass still planned. That is a sensible way to handle it in my view: a striking head that is too brittle is a real risk, and catching it before anyone gets hurt shows good judgement. The listed hardness on the post still reads 55/60, so the numbers there are slightly out of date compared with the re-tempered state.
The hammer itself is a long war pick style piece with a fabricated head on an ash shaft, made from 1041 DIN steel, and it weighs 1.2 kg. Six hours of work is a short time for a result like this. The head has a square striking face with a cross-hatched texture up front and a curved, pointed spike at the rear. Along the handle neck there are metal support plates held in place with pins, which looks like a neat way to reinforce that junction.
The fitting of the head is done the traditional way: a hard wood wedge in the middle, two round wedges, and some nails. The shaft carries charred tiger-stripe scorch marks as decoration, and the grip section is wrapped for holding.
The trade-off worth watching is the hardness question. Even after re-tempering, the maker intends to temper it again, so the final value is still open. As a proof of toughness, the hammer has already punched through 2 mm sheet steel with no damage to the head.