Ehh... Hex has a clear mechanical advantage on a Warlock, who doesn't want to spend multiple slots in a single encounter, while I think Curse's lack of Concentration makes it stronger on a normal caster. I don't think it's balance is bad so much as it's unnecessary. If you want to keep it in, I think it might be more elegant as an invocation, something like "you can cast Hex without Concentration, but it ends when the first target dies."
A one-handed 1d8 weapon is a decent melee weapon; the only real reason the expanded weapon options matter is... well, I was about to say "for the visual," but a Shillelagh-whip would be pretty sweet. Other than that, there's no real mechanical advantage. I'd be inclined to fold the cantrip into the invocation, something like:I do agree that adding Shillelagh to the warlock list carries risks. Putting the ability to wield a decent melee weapon in an invocation delays it to level 2, though.
(I'm inclined to say keep the bonus action, for what it's worth-- even as an Invocation I think casting-stat-to-attack is a little strong).Eldritch Armament
You learn the the Shillelagh cantrip. When you cast it, you may target any weapon that lacks the two-handed property with it. If you later gain the Pact of the Blade feature, you may target any pact weapon you conjure with that feature, no matter the weapon's type.