Unlimited Blade Works: The Guide to the Ultimate Paladin/Sorcerer Multiclass

[. Shadowblade .]

I see no point changing direction from Paladin until you have it. I assume you already have Eldritch Blast from Warlock 1, which is by itself already quite good cantrip, with 1d10 force damage. And it continues to improve while you level up paladin.

I suggested Lvl 5, because on this character level I could shoot two beams with 1d10+4 or +5 dmg - that would be difference +8/+10 dmg per EB salvo.