Thanks for the chapter!
Looks like he really learned how to be a blacksmith if he can fix the heroine's sword in his room without a proper forge. I wonder if he's doing anything special about the break or if author just isn't familiar with blacksmithing? Don't remember why but some kind of reaction occurs to the metal composing the break. Result is even if you melt down and remake the whole sword the weakness of the break will contaminate the whole sword making it easier to break again. To avoid that would need to melt off and toss broken ends along with a bit of the sword (to make sure removed all of contaminated metal,) before melting and reforging remainder of blade. This way would keep initial strength of sword without weakening it although would either have to make a shorter blade due to having less metal or add more metal to compensate for what was scrapped.