Well I think the first problem you have is thinking about the Warlock as a platform for marital damage in the first place. It is primarily a caster, martial capabilities will always be second fiddle for it. Also doesn't help that of the two 1st level options for Dread Armaments, you picked the one that in my opinion is a bit weaker (but still usable). What material does your table allow? Cause there's a fairly useful supplement by Purple Martin Games that might suit your desires; Manual of Adventurous Resources: Battlemages (Or MoAR: Complete for Battlemages, the other four in the series plus a little extra). What patron spell list did you pick?
Given you have Dread Knight, I think you should go to at least 7th level Warlock before going to different classes (if any others at all). 6th level would give your the Dread Rider ability, giving you a resummonable mount, and 7th would allow you to give that mount a fly speed allowing you to rain death on your enemies below. I do feel your pain about the warlock spell list (playing one in the game I'm currently in), but given the lacking spell list you should probably be thinking of using your spell points more for adding damage to your attacks. Picking up the rare version of True Strike or the Windup spell would probably be useful, since you just need to hit once and then spend 2 (4 for wind up) spell points to do damage as if you hit with two attacks (4d8+whatevs total), and then you still have a potential attack for another target or just keep on piling the damage to the first target.
I’m familiar with Purple Martins material, at the moment I’m staying within A5E official content.
“ Well I think the first problem you have is thinking about the Warlock as a platform for marital damage in the first place“
I can understand this, my counterpoint is that I’m not really building a Warlock, I’m building a Ranged Striker, 5 levels in warlock has served me well but I think it’s value is tapering off.
“Also doesn't help that of the two 1st level options for Dread Armaments, you picked the one that in my opinion is a bit weaker (but still usable).”
Agree to disagree on that one, I’ve found Combat Maneuvers to be fairly underwhelming for ranged characters.
“Picking up the rare version of True Strike or the Windup spell would probably be useful, since you just need to hit once and then spend 2 (4 for wind up) spell points to do damage as if you hit with two attacks (4d8+whatevs total), and then you still have a potential attack for another target or just keep on piling the damage to the first target.”
I’ll see if I can get my hands on rare true strike, sadly windup is melee only.
“6th level would give your the Dread Rider ability, giving you a resummonable mount, and 7th would allow you to give that mount a fly speed allowing you to rain death on your enemies below.”
I have considered this, I’m just not sure how much value I place on a mounted fly speed.
I tend to place more value on features that are more reliable and we have had our fair share of combats inside.