Hexblade with other pacts

[Rezby]

So hexblade seems obviously built for pact of the blade characters. Is it horribly suboptimal to take another pact? This is theorycrafting

[Spiritchaser]

It is not suboptimal for single target blasting with any pact

[BloodSnake'sCha]

There is no need to take blade unless you are going hexsorcadin and want a Greatsword.

Hexblade curse work better with eldritch blast as it have more damage procs.

[Trickery]

As others have said, it's good for any pact. I'd argue that Celestial is generally better for a pure-classed blaster who doesn't expect to get into melee (because of the bonus action heals that aren't spells, too good to pass up). But HexBlade is a good choice for any.

You usually hear HexBlade mentioned in the context of blade-pact warlocks and multiclass martials. That's mostly because people like going into melee and hitting stuff with weapons. It's not always optimal to do so.

Sample non-blade build: Warlock 3/Sorcerer 3, Quicken, repelling blast, feat: crossbow expert. From melee, cast EB into quickened EB and blast targets 40' away from you. You can circle around the enemy so as to aim them exactly where you want to launch them, so it actually pays to enter melee range in this case. Your AC with a shield and half plate is 19.

[Callin]

Chain on a Melee based HB is suboptimal but not horribly so I think. You can keep up some damage with Cantrip Weapon Attacks and use the Familiar to gain Advantage on the Attack. Its no GWM/PAM stuff but will still kill.

[Evaar]

If you’re going to actually melee, and you’re getting to warlock 5 and not getting extra attack elsewhere, you’ll want Blade Pact for Thirsting Blade. You could use SCAG cantrips instead but I think those aren’t as optimal as attacking twice - particularly for Hexblade’s Curse.

But it’s not an indefensible choice. You just need to build around it.

[Nagog]

Granted going Hexblade Blade Pact is a good combo, but it's also heavily focused on the melee portion. It's an amazing combo because it takes a full caster class and brings them into the realm of martial while still keeping pace with many base martial classes. However, My personal opinion is that neither Blade nor Pact quite compares to Tome, as having access to any ritual spells I'd like and all of the fun invocations available to TomeLocks makes it far superior to Blade and Chain. The only way Blade comes close to this is not having a weapon bound to you and being able to summon any sort of weapon you want at any time. While the straightforward benefits of this is being able to choose the damage dice of your weapon, the lesser used function of this has nothing to do with combat at all. For example, you need something to tie somebody up? Summon a Spike Chain. Need something to block a doorway? Long hafted warhammer. Need an impromptu lockpick? Stiletto knife. Out of combat potential is amazing if you think outside the box. Sadly, this potential becomes moot if you bind a pact weapon to you.

[SLOTHRPG95]

Tomelock provides you with extra cantrips, which in turn makes having to take a SCAG cantrip as one of your Warlock cantrips (to be able to melee well-ish) less of an opportunity cost. And as noted above, ritual casting is really good. If you go Tomelock on a Hexblade w/ a SCAG cantrip, you have three roles covered reasonably well: melee combatant, ranged combatant, and out-of-combat utility. Plus, don't forget that with Wrathful/Branding/Staggering/Banishing Smite (switching them out as you get better ones), you can trade spell slots for damage even without the Eldritch Smite invocation.