Rising Fire

Rising Fire (ライジングファイア Raijingu Faia?) is a fire-elemental Special Weapon that Mega Man X obtains from Magma Dragoon in Mega Man X4. When equipped with this weapon, X raises his arm in the air and shoots a fireball upwards. Because the fireball that is shot out only goes straight up, this weapon has very limited horizontal range. When charged, X preforms a Shoryuken-esque flaming uppercut that makes him go up in the air for a bit, and after the uppercut has been executed, a large fireball is then shot upwards, similar to the weapon's normal fire. Whether this weapon is used in its normal or charged state, Rising Fire can also be used to burn the wooden pieces and certain foliage in Web Spider's stage.
This weapon is the primary weakness for Frost Walrus and Reaper Sigma's first form. In Reaper Sigma's case, however, Rising Fire is the only weapon that can damage him, as his cloak will otherwise deflect any other weapons - including even X's X-Buster and the Nova Strike.