Is that stat array kosher? I think there's one too many 16's in there (typo?).
If it is, it looks great. Slap a big bunch of armour on top of him, hex all the things, and have a bit of backup blasting and spell utility to boot.
I'd kind of be tempted to go the heavy fighter with warlock support route myself. Pact of the Blade doesn't exactly give you a lot, and burns one of your invocations for the 2x attacks.
Fighter 1->Warlock 2->Fighter 5(BM) gives you plenty to work with, and then you can grab more magic if wanted down the track. AS, BM dice, Hex and EBlast are all there, but you haven't strayed too far from a good fighter build to get it.
Then dump in a warlock level if you want your pact boons and level 2 spells, or save the levels for something else (there's plenty of charisma casters available if you decide to go a different magic route) or just more fighter levels. It also frees up your pact completely, so you can grab an invis familiar or rituals (and a normal familiar) if you want.
Armour of Agathys is nice for a combatty non-concentration spell, but Charm or even Expeditious Retreat might be just as handy. You know that there's going to be at least some RP or movement based challenges for your party to get through considering how many fighters types you have in the party, and either spell helps you breeze past them, while still being useful all campaign. Ex. retreat is only let down by its concentration, which will mostly be used by hex.
Mage Hand or Minor Illusion are always handy to have in your kit too. Neither are concentration, so you should be using them any time you're not attacking. I like Mage Hand myself, but Minor Illusion is far more versatile (but is pretty DM dependent).
Mirror Image is amazing for combat, Misty Step is handy for pop movement, and Suggestion is right up there with the most broken of spells (save and DM dependent though, see if Hex does saves or just ability checks). I'd probably pick one of those three when I grab Warlock 3, because they're all just as good as a Devil's Sight/Darkness combo, but don't annoy the rest of the party. Spider Climb is also a vastly underrated spell for a mêlée/shooter hybrid. It doesn't exactly look like flying will be your party's forte, and you can do a heap of stuff with it when needed (even if it is concentration, don't fall to your death from damage).
Going the heavy fighter route also gets you more ASIs, so you can feat out if you want, or just boost whatever stat is doing the most work for you. By the end you'll be a Fighter 12/Warlock 3, which ain't to shabby for combat or casting, and nothing really got wasted along the way. Plus you'll have a familiar or a few extra cantrips, which is nicer than an on-call weapon could ever be.
I'll chuck together a build off the standard array shortly (it'll probably be a Half Elf, but then you don't need devil's sight, and the fighter levels "eventually" make up for the loss of an initial feat. And it gives a bit of basic resist vs charm from the post below).