[@TechnoWizROK]

Okay, my thoughts are as follows.

Firstly. He is 17. [i]17[/i]

With mastery of three unique and powerful magics, and "Possessing a prodigious knowledge of all known runic languages and then some".

Learing anything takes time, lots and lots of time. Even if he was taught from a young age, there would not be enough time for him to effectively learn even more then a single magic.

The Unicorn blood. Look, with all the other stuff he has going on here, the implications of him possesing something like that is enormous. It also doesn't fit with his personality. Pure of heart? No.

The Rune mastery. First part aside, the way you have written it, is too damn powerful. Blocking medium grade magic on a whim? You are basically saying he is invincible to all but the most devastating of spells. But with preplanning he can block a spell like Abyss Break? Hell no. Abyss Break is on par with Fairy Law, which is in turn, on par with Etherion (you know, the satellite square capable of destroying cities or even countries?) in complexity and power. 

Teleportation (a-la flying raijin jutsu straight outa Naruto) the problem with this is it is already an extremely powerful ability in the right hands, and you have just added it on to his kit like it's nothing. Instant teleportation. Let that sink in.

Zarkoon-sama summed up my thoughts on Imperial Eye pretty well.

And did I mention that all this magic and power is in hands of a "impulsive and overconfident" 17 year old anti hero "with little regard for the consequences of his actions" who is trying to topple a kingdom?

...oh, and where the hell did he get [url=http://typemoon.wikia.com/wiki/Ea]Ea[/url] from?

To clarify what Caits said, she has explicitly decided that she will not be accepting S class wizards right off the bat.

The backstory, the most important part to me, is passible by canon standards, but it has a few problems bynthe RP. Firstly, his family would have been hunted not long ago in what is basically the salem witch trials, the inquisition, and the crusades all wrapped in a lovely ball. Yet there is no mention or adressing of this. Even practicing his magic should have drawn unwanted attention. And that's just the start. Don't get me started on demolition an entire stronghold with magic.

Considering all the tension between mages and non mages at this point (especially after the arc we just went through, but you had no way of knowing about that, so I don't hold it against you) an act like that would have gotten him hunted down and arrested for sure.

To sum it up, your character is far too young to be so powerful, his backstroy needs some fleshing out, and his personality is one step from a full out homicidal anarchist villain.