3-Socket Phase Blade

[Zzabur]

So, this is what i want
Superior Ethereal Phase Blade
+15% ED, 3 Sockets
(yeah, right)

so i can make a crescent moon for my frost zealot.

Beeing realistical, any ethereal phase blade would do. I heard that ethereal dimensional blades can be upgraded via the cube recipe... Is it the same as for uniques? Do i have to make the runeword before upgrading? (so it becomes kind of unique) Can i upgrade AFTER creating the runeword?

The AS states than "ethereal items can be upgraded with this recipe" does it refer to ANY ethereal item, just unique ethereal items, or also regular ethereal items? Can a regular item be upgraded?