I have been told that korean four tiger swords are forged on the hour of the tiger, on the day of the tiger, in the month of the tiger, in the year of the tiger, which gives them extra juice against spirits and evil etc. That's totally awesome, but how is it done practically? Because that gives them one hour every twelve years to work on it.

Do they have to work for one hour, then wait twelve years to resume work? What about all the spells and constellations inlaid into the blade? Does that work all have to be done on the hour,day,month and year of the tiger too? These swords would have to be like a century old by the time they are finished making them right? That would be pretty awesome, but it sounds unrealistic.

Is it possible to forge a decent sword in one hour? Do they just have to start or finish on that magical hour?

What am I missing?

I think the idea that it is supposed to be hard to do is part of the idea. Kind of like seventh son of a seventh son. Also, apparently Tiger hour is from 3 to 5, so actually two hours. Still, seems like a short time to make a sword. Since the idea is part of the zodiac, maybe the principle is to birth. An actual birth can last some time, but I am guessing that for a zodiac, what counts is when the child is born, not when labor started. So maybe it is the finishing steps of making a sword that count for the sword's zodiac.