To defeat Brother 6 with the flamethrower, start by either running a circle around him until he stops shooting fire or hit you with the fire. If he hits you, he will laugh and give you an opportunity to attack. Use the Square Slash to stun him. Next, use the Square(4) combo until he shoves you away. After hitting the ground, immediately use the Square Slash. If done fast enough, you will interrupt his attack and stun him. Repeat the combo on him, then repeat the entire process through all of the phases.
Defeating Daimyo
You will know that he is about to do a big attack when his weapon sparkles. Time your blocks to parry his attacks. When he is open use any desired combo until he backflips away. Repeat this until he has been defeated.
Defeating Sword Master
Time your blocks to parry his attacks and leave him open. You will know that he is going to use a big attack when his weapon begins sparkling. Use any combo until he begins blocking. After you have locked swords with him twice, he will become faster and stronger. Continue to parry him and combo back if you are skilled at timing your moves. Otherwise, Focus Dodge and attack.