Description
This Bio is updated regularly with new information, magical, non-magical and other things all the time.
Full size image of Flint: Flint (Equestrian)
Flint’s Cutie Mark: EXP Restoration Phoenix/ OC Flint Cutie Mark
EXP Emblem: EXP Emblem
Flint's Reference Sheet: flintexp.deviantart.com/art/Fl…
Flint's Uniform, Equipment Colors, Como Styles have changed. Look here for all Flint References/ Colors, ect.: flintexp.deviantart.com/galler…
Flint’s variations created by other people which include uniform, weapon, jetpack wing variations: flintexp.deviantart.com/favour…
Flint, Phoenix and all EXP items (C) 
Half-Life 2 things (C) Half-Life 2 (C) Valve
While I like the overall idea of a Determinator-esque character akin to B.J. Blazkowicz from Wolfenstein or Morgan Freeman from Half-Life who's sole purpose in life is to handle wars, violence, and situations no other pony can, I have... a few issues with his skillset. You've probably heard "it's a little much" quite a few times now... and I gotta admit, I have to agree with them.
Let me give you an example: Right now, I'm working on a MLP: FiM fanfic. I don't plan on including OCs in the plot, but if I wanted to include this OC without his almost-comically huge arsenal of abilities leeching the tension out of every physical or magical conflict, I'd have to first have him caught completely off guard by the main villain's magic-suppressing machinery and get captured as a result, and then have the main villain rip out his horn, not only stripping him of almost all of his magical abilities and leaving what magical talent he still has severely handicapped on account of the way his damaged horn causes any spell he casts to be chaotic and nigh-impossible to control but also inflicting brain damage that results in him losing a significant portion of his knowledge and experience, on top of his backpack getting damaged in a way Flint can't fix without the knowledge he's lost and losing much of it's functionality. It's admittedly kinda cruel, yes, but it also drives home the main issue with this character; while a guarentee that Flint can be placed in any scenario, adapt to it, and eventually pull a positive outcome out of it is a nice thought, the knowledge that a positive outcome is inevitable the minute Flint gets involved quickly destroys any and all stakes.
Of course, all this bashing of your OC's flaws is useless without any advice on how to fix them. For that, I'd like to point you to Morgan Freeman and other Determinator-esque characters like him. They didn't need immortality and absurdly advanced self-made gadgets and any other fancy tricks to get a positive outcome for their stories; just a good helping of both brains and brawn and an indominable will. The same could be true of an updated version of Flint, one where all his Gary-Stu-esque powers have been replaced by a simple tendency to never, ever give up.