ethereals

[adeyke]

Phase Blade=level 54 to use(base)

That's the base.

Dex needed=136(str is more or less irrelevant, since all classes except sorcs start with 15-25 str)

Yes.

Ethereal Phase Blade=123 dex(give or take a point) and 23 str(+/- 1)

It's 126. 10 less than the non-ethereal one. We are talking about one without any -% requirements, no?

alvl to get cruel(or what?) 450% affix=56? Might be possible to roll for a soldier's/master's(except the top 2 of that affix set), to push for it?

450% is the result of two affixes:
Master's requires alvl 56+ to spawn and clvl 48+ to equip
Cruel (the new rare-enabled one) also requires alvl 56+ to spawn and clvl 48+ to equip

So a rare sword with alvl 56 can get both of these, and if they're both perfect, it's 450%.

So theoretically, if one can get to level 52 or so, one could imbue a crystal sword and hope for 450% ED?

You need at least 57. That would give ilvl 61, the minimum required to get alvl 56+ on a crystal sword (qlvl 11).

What I'm worried about is that the upgrading will raise the level requirement beyond what I'm willing to "pay"(in terms of time and energy spent)

A 450% phase blade found like that would require clvl 54+ to use (and there's no way for it to be ethereal).
A 450% dimensional blade upgraded to phase blade would require clvl 59+ to use.
A 450% crystal sword upgraded to dimensional blade and then to phase blade would require clvl 66+ to use.

Of course, if you also have affixes that require a higher clvl to use, the numbers would be higher.