Sharp Knuckle is a Master Weapon usable exclusively to Knuckles Man that appears in the Mega Man and Sonic the Hedgehog comic crossover event, Worlds Collide, published by Archie Comics. Sharp Knuckle allows the user to smash their foe(s) on the ground with their ingrown-spikes on their knuckles, hence its name. Although it is Knuckles Man's exclusive Master Weapon, Mega Man can also use the Sharp Knuckle Master Weapon for his own usage if Mega Man copies the Master Weapon with his Copy Chip from the Roboticized Master.
When Mega Man uses this move, his regular blue color scheme is switch to a white and crimson color attire, similar to the color scheme of Knuckles Man's non-roboticized counterpart, Knuckles the Echidna. This is the only Master Weapon that Mega Man had used in Worlds Collide that was used only once, with the rest of the Master Weapons that Mega Man absorbed being used more than once.
To this date, Sharp Knuckle has only appeared in Worlds Collide, and with the natural events of Mega Man's world restored, it is assumed that Sharp Knuckle will not appeared again in the Mega Man comic series.