I think your style of pony art is a little... weird. But I do love the detail you put into that shotgun. Also I'd argue about Blackjack's coolness but I accept it's all a matter of perspective and can be influenced by any number of things. For example I've read loads of FOE fics, so I've got a bit of a broad range of protagonists to compare Blackjack to. Rambling on coolness aside, I also want to mention that I enjoy your use of light, shadow, colour, detail and rain effects. Maybe make Blackjack's muzzle a little bit longer and this one wouldn't look as weird to me.
If you're just getting started in FOE fics, then I have a few I highly recommend.
The First couple I recommend reading are Pink Eyes, Heroes, The Last Sentinel & Murky Number Seven. Each of them has a very different tone to one another.
Pink Eyes being more about childlike innocence in a place like the wasteland
Heroes questions the nature of heroes and ponies in general.
The Last Sentinel is told by the Narrator, Frost Windchill as he is telling the story of his life to an audience of ponies, griffins etc. Makes it feel really unique as you get occasional interruption from the audience too. The audience of course ask questions which allows the author to clear up details.
Murky Number Seven is the story of a lifelong slave in Fillydelphia and his desire/drive to escape and be free.