As it stands, eldritch blast is a standard action ranged touch attack (as far as I can comprehend it), which deals 1d6 + 1d6/2 class levels after the first, so you deal 1d6 at 1st level, 2d6 at 3rd, and so on. Since it can be used at will and improved, it's not so bad to have. At 15th level, the warlock uses two blasts instead of one, but at full power. Eldritch Glaive (which forms a weapon) and Hideous Blow (which adds the EB damage to the weapon) allow you to use your BAB for multiple applications per round, but essentially only at melee. Eldritch Claws allow you to form claws, which work as natural weapons (IIRC) that deal EB damage; if you find a way to make multiple natural attacks, you can deal multiple EB damage (particularly with Pounce).
What I propose is very similar to how I worked it out; I don't like to show off my work, but that doesn't mean I can't use it as an example. Dual Blast as presented is an actually good idea: you tie it to class levels rather than your BAB, which makes Eldritch Glaive and Hideous Blow good for multiclass characters and prizes fidelity to the class. However, two blasts at that level doesn't seem much, when a Rogue can chuck six splash weapons and deal its sneak attack damage at range, ignoring Dex AND making it ranged touch attacks. All it requires is a potion of greater invisibility and many flasks, of which you can have with different flavors, and technically it works right from Core. This may seem really exaggerate, but to keep up with that top of damage, or even lower limits (the humble Power Attacker, for example), you need to deliver some reasonable options.
Lowering Dual Blast to 8th level, or even to 10th level, allows the Warlock to become pretty competitive right at those levels even from afar. Melee-locks would still have the advantage, as since their amount of hits is based by their BAB (or really, their iteratives), they take advantage of Divine Power, as well as any "extra attack when making a full-attack action" buffs (Hideous Blow and Eldritch Claws, particularly). Dual Blast behaves differently, as it negates many of the chances of landing a third or even fourth blast, because it requires a full-round action instead of a full attack action. Note the big difference, and that's something which works right as you're working Dual Blast right now.
These would be my responses to the two concerns regarding Eldritch Blast: why choose Hideous Blow/Eldritch Glaive if I can do the same hits while at range (second response)? Will Eldritch Blast do too much damage for an "at-will" ability (first response)? If you find both answers to be conclusive, then you can see why placing a "Triple Blast" ability between levels 15th-20th wouldn't be a bad idea. Since it doesn't depend on your BAB but rather on your class levels, only those Warlocks that remain up to 14th level have a chance to get three attacks, and still get all the other loads of goodies, whereas those who decide to multiclass will probably miss the benefits (particularly if Triple Blast becomes a 20th level ability).
Almost like if you read my mind. Yes, I see Giants as the "crafting" ancestry, giving it something different to work with aside from "titans or ancient awesome civilization".Hmm...an interesting point, I can see where you're coming from. I couls see possible switching Imbue Item and the Giant's Eldritch Soul, making Giants the premier forgers, instead of having all warlocks good at it.