What exactly is a Magistra? Is there a list of them?

Name: Minato Morimoto
Age: 17
Gender: Male
Race: Human

Personality: Minato acts much older than he is, even his speech is strangely archaic. He has adopted the mannerisms of his old master, and adheres to the same, strict moral code. He spends a lot of his free time reading, writing or simply relaxing outdoors.
Appearance:
Minato strikes an elegant figure, from his brown hair tied in a ponytail to his slim features. He wears the clothing of his home village as taught to him by his master, which generally consist of a loose fitting robe tied around the waist with a sash, a long plaited skirt and wooden sandles. (For those of us in the real world it's a traditional japanese outfit)
[img]http://img1.wikia.nocookie.net/__cb20121110070307/destined-dynasty-warriors/images/3/35/R169_457x256_6988_Rurouni_Kenshin_2d_fan_art_snow_sword_anime_samurai_manga_katana_guy_picture_image_digital_art.jpg[/img]

Knight's Raiment:
天カット [Heaven Cut]
A Katana that does not cut immediately, but instead delivers it's blows all at once when the blade is sheathed.

Other Weapons:
後悔の剣 [Sword of Regret]
A normal Katana Minato uses when he cannot use his Regalia. Drawing this blade means he has made a grave mistake, and he will sometimes fight with it first as a symbolic gesture.

Skills: Cooking, Research, Kendo, Katana Forging (Can be applied to other things), Calligraphy
Magistra: 
[First Seal: Release] - Minato releases the first set of his body's limiters, allowing him to become faster and stronger at the cost of using more energy.
[Second Seal: Release] - Minato releases the second set of his body's limiters, becoming signifigantly faster and stronger and also healing faster, but expending much more energy and creating more risk for damage.
[Third Seal: Release] - Minato releases all of his body's seals, becoming immensly powerful by burning his own life force. He has never used this Magistra, for obvious reasons.