Vedalken Eldricht Knight

[adb82]

With a 13 WIS, Tempest won't be giving you much nova damage, and Spiritual Weapon won't be very useful either. Your +1 WISMOD will cause your spell DCs and attack bonuses to be pitiful, especially since it's going to be Tier 3 before your Tempest Cleric damage spells start to become available.

So either way, if you go Cleric/Sorcerer/Wizard after EK 8, you're going to have to stick with spells that don't rely on your INT/WIS/CHA score. That means no attack spells or save spells. Stick to utility spells, defensive spells, and buff spells. But you'll primarily be using upper level spell slots to upcast Shadow Blade anyway.

True, but once i get my first 3 asi's (warcaster, elven accuracy, resilient wis) at lv 8, the others can be take to bump wis to 16/18 (even 20 wis, if it will get to lv 20), and anyway it won't get spiritual weapon before character lv 11, while at lv 12 it can have already 16 wis (18 wis at character lv 16). The same can't be done with int or cha because resilient is kinda useless in that stats. But I agree with you that the war wizard rute (divination and chronurgy also are nice, but I still prefer war magic) is more optimized.
I really love the Gloomstalker option, especially for thematic reason (but that attack in the beginning of the turn that stack with action surge it's also huge), unluckily I'm not sure we ll get lv 16 for get also the war wizard archetype, but if I'll feel that Resilient and maybe lucky is enough for the mental defences, and that i don't need that many upcast of shadow blade, i would love to try it after lv 11. Unluckily it don't stack with war magic, so i can't add it in before lv 11, this make me think that the Bladesinger would be better for it, as it's double attack with cantrip stack with the Gloomstalker attack, he has better spells, earlier shadow blade, more slots, at the cost of couple lv delay on the second attack, assuming starting fighter for con saves. In theory a triclass echo knight/Gloomstalker/bladesinger could work well, but it need int and lots of ability score improvement, so probably in practice it's not that playable, even with my stats, while probably echo knight4/bladesinger x (starting with fighter 1/BS 6) or Gloomstalker 4/bladesinger x (going first BS 6) can be less difficult to build, but probably the bladesinger is better straight, without multiclass it, and that's the reason why i normally don't play it unless i want to play a wizard with insane AC, as after lv 9 it will probably play mostly as a wizard and rarely as a gish.

Ps of course any Bladesinger multiclass should start int 16, con 14 somehow.