TSUIHO SARETA OSSAN TANYA SHI, NAZE KA DENSETSU NO DAIMEIKO NI NARU MUKASHI OMOCHA NO BUKI WO TSUKUTTEAGETA KODOMO TACHI GA ZENIN EIYU NI NATTEITA

Description

The protagonist, Delate, is a 40-year-old blacksmith working in a provincial city. One day, he is suddenly banished by a colleague from the guild.
He then heads to the royal capital relying on a letter he received from a girl for whom he had previously made a "toy weapon." He finds that the "toy weapon" he made has evolved into a legendary weapon, and the girl has become a national hero!
He makes a huge turnaround from being an unemployed old man (40) into a hero who has made a legendary weapon!
He also unexpectedly reunites with the colleague who kicked him out, and takes him on as an apprentice!?