The soulknife I find to be pretty cool in that you can manifest your own weapon. If anything, the 4E swordmage seems to resemble the soulknife, but in an arcane flavour.
Shadowblade. Assassin paragon path, manifests her own weapon, with enhancement bonus from her Ki Focus. Check it.
Only problem with it is that they need to make Ki Focuses treat affected weapons as if they're magical (or the Shadowblade won't be able to multiclass into Ranger/Rogue properly, as not being able to do burst attacks with Focused Expertise makes a multiclass Shadowblade sad).