He trained the Baronet Barnard, who didn't heed close instruction and was too impatient to learn all that he could. He refused to train young Elsa by reason of her being a 'mere' girl, though he admitted that she had natural talent and played close attention.
His speech reveals an arrogant man, but his skills are the real deal, and for a gold coin he'll have a sparring match with a Fighter and give some pointers upon the hero's most-probable defeat, and he'll be civil and respectful enough while this process is ongoing.
Should the hero actually best him, the Weapon Master declares he's going to retire after being beaten by a such a clumsy lout, he'll wish all kinds of misfortune on the hero, and he will not be seen again. The hero must be as strong as he can be in pretty much all his combat stats, and get his timing for blocking and attacking correct, making the Weapon Master the greatest challenge for a Fighter in Spielburg.
The Master appears semi-randomly in the central court of tha castle practicing. His appearances are not in a fixed hour. Whenever he trains the hero, he won't appear again until the next day.
It should be noted that the player's inventory weight is a factor in the fight with the Weapon Master and the player should drop all the items they can before the fight and remember to pick them back up after.