I've found three basic builds for warlocks:
1. The "classic" Chr-based EB warlock: War X, focused on Chr (with Con secondary)
2. Dex-based bladelock: War X, focused on Dex and Chr
3. Str-based bladelock, Ftr 1/War X or Pal 2/War X, focused on Str and Chr
The first and third are disallowed by the rules of this thread, and the second has a good write-up on the first page. I don't know that you're really going to find a lot of options that are mechanically distinct from these in pure warlock.
Despite the "no multiclassing" rule, I'm going to talk about my own experience playing #3. I'm playing a fiend bladelock Ftr 1/War 5 right now. I have EB, but no AB and I cast it very rarely; my primary role is party tank, using longsword + shield. (I went variant human as Ftr 1 to take Heavy Armor Mastery, which synergizes very well with the temporary HP.) I have Fiendish Vigor, Devil's Sight, and Thirsting Blade as my invocations, and while AB is a possibility in two more levels, it's by no means a certainty. I think my damage output is actually higher with throwing axes than it is with EB, and as I'm prioritizing Str over Chr, I don't think that AB would change that. I usually use EB instead of axes, but mostly for flavor/story reasons.
Playing the character has felt anything but repetitive. At lower levels, I would often cast Hex or Hellish Rebuke, but as I've leveled there's great tension between Darkness, Fireball, and Armor of Agathys for my limited spell slots. The character essentially plays as a fighter with a limited selection of spells to cast and a periodically-refreshing pool of temporary hps.
Honestly, I think they made a relatively large design error in not giving the bladelock access to heavy armor -- it requires a decent investment in Str to use effectively anyway, so it's not exactly a free-roll, and it would enable the kind of Elric-inspired character that I think a lot of people wanted it to be without requiring multiclassing. I think that topic has been discussed to death in the past, though; I know I've probably put in a dollar's worth of my two cents in older threads.