|Title:||Bridle of Chivalry|
|Transliteration:||Kiei no Tadzuna|
|Owner:||Rider, Rider (Fate/Prototype)|
|Maximum number of targets:||300 people|
Bellerophon: Bridle of Chivalry (騎英の手綱, Kiei no Tadzuna?) also known as Reins of Pegasus (in Fate/unlimited codes), is a shining golden harness, bridle, and saddle set capable of fully controlling a divine beast. It has no effect by itself, but once fastened to the mount, it increases all attributes by one rank and allows for the beast to use its most powerful charge to physically destroy the target. It must be fastened after the mount is summoned or simultaneously as it emerges from the summoning circle. It is an attack supreme in attack and defense, capable of killing any servant directly. The "Armor Class" rank is raised by one hundred, and the maximum speed that the charge of the beast can reach is between four hundred and five hundred kilometers per hour. Rider uses Bellerophon on her personal mount, the mythical winged horse Pegasus. While summoning a legendary beast is an ability rivaling that of a Noble Phantasm, it is done independently of Bellerophon as one of Rider's innate abilities possessed due to her deeds as a Heroic Spirit.
It is an abnormal Pegasus that has lived from the Age of Gods, placing it at the level of a Phantasmal Beast rather than the normal rank of a Monstrous Beast. It is a divine mystery with magical protection even greater than Saber's, allowing it to easily brush past modern thaumaturgy and Invisible Air without halting its charge, and it has one hundred times the magical energy of an average magus. It is close to the level of a dragon, and its divine protection is already on the same defensive level as one. Coupled with Bellerophon's already high defense, it allows for an even greater defensive ability than normally possible. The buffets from Pegasus's wings are capable of generating massive shock waves, which raze infrastructure and lacerate the bodies of living beings. It is normally a docile being not fit for combat, but it will rage and attack the enemy once the reins are used to compel it to fight.
She summons it by slashing her neck with her dagger, allowing the blood to spray out and stop in the air to form a magic circle. The circle, which displays a creature-like figure, swells with a large amount of magical energy, which is enough to have come from a few hundred magi, far surpassing Blood Fort Andromeda. Pegasus then emerges from a giant eye bound by blood. This is in references to the Pegasus, the son of Poseidon, born from the blood of Medusa's headless neck, and later tamed by the young prince named Bellerophon. If Rider is on the ground, she can immediately use Bellerophon to fire Pegasus at the enemy like a arrow of light without having to personally ride it. If she is in a suitable area for aerial combat, she can utilize it as a normal summoning to allow her to mount it. Once in the air, she can constantly attack the enemy and leave their range without giving them time to counterattack. It attacks the enemy with overwhelming magical energy like a mobile castle wall that doesn't give the opponent time to dodge or defend, and she can utilize Bellerophon at any time to to cut all of the Pegasus' limiters for a final attack. With assistance from Shirou's Rho Aias, it is capable of defeating Excalibur after ninety percent of Bellerophon's light is offset.