I was thinking about this yesterday, in fact.
I agree that Warlocks as presented here are very dip-worthy. It's actually quite nice -- Fighters have always been worth a level or two for many builds, and now Warlock and Barbarian are as well, in my view.
Is it too much? We'll have to see.
Two arcane list cantrips. Barring combo specific synergies & possible changes to cantrips I'd imagine these to often be something like guidance & resistance
There are lots of ways to get attack cantrips, and they are the only ones I would be concerned about here. For most builds, this will be an alternative and not the primary attack.
The Blade will be primary. It will be a good dip for base Wis classes (Cleric, Druid) and Cha-classes (Sorcerer, possibly Bard). More interesting, is it will allow things like a Wisdom-primary or Charisma-primary fighter. That's a win, in my books, because it leads to a greater diversity of builds.
Who potentially benefits most are Paladins, Rangers, etc., but it's not clear that they will be more effective than a rapier-build. Anything that reduces the importance of Dex increases the available builds, and is a good thing, for me.
As for the other pacts? All of them give access to a regular find familiar, but Chain gves you a super familiar (good for narrative, not overpowered sinceit has to move after your turn now); Book gives you rituals (which is on par with the Ritual Caster feat as presented earlier. Much less interesting than the 2014 Ritual caster, since you are stuck with level-1.
And the spellcasting is not meaningfully beyond what many races are given. A level-1 dip is desirable to many, but needed for few.
Now, at level 2 you get invocations. These are fun bells and whistles, now available without needing a pact with an extra planar entity. I'll go through your list, because we see these differently, I feel. I think different tables will see their values differently. I see these as fun, but not OP.
- Agonizing Blast: EB scales by warlock level, total nonissue. Great for no prereq invocation
Agreed. Better than a heavy crossbow, if that's what you want.
- Armor of Shadows: free mage armor casting without needing to prep or use a slot.
This benefit was previously available with a 1-level Sorcerer dip. Needing 2 in Warlock does not overpower it. Good for aesthetics, but not for optimization.
Improves out of combat events. Good.
Good for races without darkvision already, but probably not a go-to for those with. Not broken.
- Eldritch Spear: Links to EB & EB only scales by warlock level now
Dud for dippers (and for everyone?)
- Eyes of the Runekeeper: If an ability forces the GM to write everything not written in common in the form of code or riddle it's probably too good for the dip
Some DMs want their players to have fun. This is that -- a minor ability, less than a level-1 ritual. Not overoptomized, but fun for players.
- Hexer: 600ft range on hex & advantage on con saves to maintain concentration. Not sure how I feel about this but it's probably fine
Ha. I thought this one was potentially OP; makes it parallel to the level 1 Ranger ability Favoured Enemy. Fine.
- Lesson's of the First Ones: Gain a first level feat of your choice?... no this is way too good for part of a dip on top of everything else the dip grants. It should absolutely have a higher prerequisite even if that results in feat+something else
Which firslevel feats concern you? Lucky is the only one that concerns me.
- Mask of Many Faces: Disguise Self without expending spell slots?... this only gets better the higher level the PC with it gets. This should absolutely not be available at level 2
Compare the Changeling. Powerful, but not OP.
- Misty Visions: Cast Silent image without burning spell slots. cool, fits great for a very small part of a dip
Adds Fun.
- Repelling Blast: EB scales by warlock level, total nonissue. Great for no prereq invocation
Adds Fun, from time to time.
So yes, a 2-level dip comes away with some great Utility, but it's not clear to me that it's going to be worth it for most characters. I guess we'll see.