Guardian Soul

Guardian Soul (ガーディアンソウル) is a Keyblade in Kingdom Hearts II which is given to Sora by Auron after he defeats Hades and restores Auron's will. Its name comes from Auron being a Guardian of Yuna's in Final Fantasy X.

Appearance
The blade is similar to Auron's strongest weapon in Final Fantasy X, the Masamune. The teeth appear to be one side of the spirit of Yu Yevon. The hilt guard is a strange face while the token is Auron's jug of sake. In addition, the sparks that appear when the blade is used to strike as per other Keyblades are Yevon symbols, a reference to the main plot of Final Fantasy X. This is, however, ironic, as Auron was instrumental in revealing the truth of the religion.

In Combat
Guardian Soul can be useful in many situations, as it has a fairly good reach and (with a strength stat of +5) has the roughly third highest strength bonus in the game (while other Keyblades also have +5 strength boost--such as Sleeping Lion and Rumbling Rose, very few are any higher than this). Furthermore, the ability on it, Reaction Boost, increases damage dealt from reaction commands, therefore making such fights the Master Control Program battle easier.