Eldritch Strike: It does more damage than eldritch blast, hits a different defense, slides things, works better with leaders, and you already have a ranged attack in the form of your other at will. And doesn't burn a feat, and can do pretty silly damage (for a Goliath Warlock) at level 1). So better all 'round, really.
keterys: *nod* on radiant weapon--though without Student of Caiphon(wrong pact), it basically means you're concentrating more on your Eldritch Strike (as you get to keep using a greatsword or falchion, rather than devolving to staff damage/proficiency), and avoids having to have painful starting 12s in Wis and Dex (hurting your reflex and AC, though Staff Fighting helps a bit there). But I'm not sure you can pump up your Implement damage to the point where it competes with DWP/Ruin levels. It would be nice if the melee-ish warlock had a bit more support, really; there are great dailies like Armor of Agathys, and a few close blasts, and Infernal "revenge" abilities, but beyond that? Nada.
edit: Oh, right, syberias shard of radiance. Ok, yeah, even without Caiphon or vulnerability tricks, that brings radiant weapons back into parity nicely.