@stilgar and
@Askorti It is probably a sort of bastard sword, it isnt unheard of that "one handed" swords have bigger grips, so you can use them two-handed, which drastically increases the speed a sword can be swung, so even for a normally one handed sword it can be useful and there is no real problem as long as the balance is still good for one handed use.
@RemIpsum It doesnt say one day tho? Sure there is the "worked all night"-thing, but that can also refer to just the finishing process. Thats what i would guess, because yes, a "masterpiece" as its described isnt made in a day
(but very simple swords can be finished in a day)