It depends on your build, really.
I wouldn't go with a sorcerer power, as you're probably going to have implement problems. Even with an MC feat, you won't have a decent dagger or staff handy.
Hmm ... unless you use a dynamic weapon, I suppose.
Hmm .. if you go with an 18/18 (con/cha) build, the con-based warlock powers are also nice. Throwing Pact Initiate into the mix, you'll have synergistic implement choices.
For instance, you could decide you like axes. You could use an axe for your weapon powers, and a wand for your bard & warlock powers (including the dilettante one).
An example of half-elf bard/warlock choices:
Assuming 18 con/ 18 cha, versatile master.
Pact Initiate (Dark Pact): Spiteful Glamor is D12 + cha damage vs. uninjured target. Useful as an encounter power. Training in warlock implements.
Dilettante: Hellish Rebuke. Just wade right in there and use it. Flank with your defender. Deals double damage if you get hurt .. including being hit for provoking an OA (last round's hellish rebuke).
I don't really like eyebite 'cos your target will simply attack someone else. When teamed up with a skirmishing swordmage, dire radiance is awesome.
Edit: procedure clarification