tempering (metal); annealing; forging
toughening; disciplining; training
彼は長年の修行で精神を鍛錬した。
He trained his mind through many years of ascetic practice.
刀匠は鋼の鍛錬を重ね、名刀を完成させた。
The swordsmith repeatedly tempered the steel and completed a famous sword.
職人は日々の鍛錬こそが、技術を極める唯一の道だと教えた。
The craftsman taught that daily training is the only path to master a skill.