Flame Sword

Flame Sword (フレイムソード) is Sword Man's special weapon. It's a close range weapon, but is capable of igniting things, such as the Thorn Vines in Search Man's stage. It's especially useful on Search Man himself, as it can burn down the bushes he hides behind and prevent him from ever using his Homing Sniper.

Also notable, this weapon is the most effective special weapon for fighting the second form of Dr. Wily's Wily Machine. 

Trivia

 * Because of the somewhat poor voice acting on Mega Man's English voice actor's part, the word "Flame Sword" is not pronounced properly in the game. Normally, the word "sword" is pronounced as "sohrd" -- in-game however, it is pronounced with an extra "w" in the word sword, thus resulting in Mega Man saying "Flame Sward" instead of "Flame Sword".
 * The Flame Sword was made into a Battle Chip in the Mega Man Battle Network games.