A Higher Level Hybrid Swordmage

[Yakk]

Sure, that also works. If you do so, I'd go shielding swordmage then.

Con is needed for various thunder feats.

At level 11, you have 7 feats (8 if human).

Expertise of some kind is needed. Note that essentials expertise feats don't work with swordmages very well (as you need one for the weapon, one for the implement, and no implement expertise (heavy blade) exists.)

Light blade is a definite option. You don't use your [W] that much, so going Rapier instead of Longsword gives you access to light blade feats.

For optimization purposes, you typically over-optimize a single at-will, then save encounter powers for situational and/or boosts.

So here is a set of 8 feats that does interesting things by paragon:
Expertise (weapon of choice)
Arcane Admixture (thunder) on Sword Burst
Resounding Thunder (thunder powers gain 1 radius 13 con)
Battle Awareness (fighter MC, encounter interrupt power 13 str 13 wis)
Polearm Momentum (fighter, 15 dex 15 wis, push prone if you do 2 squares of forced movement)
Mark of Storm (slide 1 when you hit with thunder power)
Hybrid Talent (Swordmage Warding)
Greater Swordmage Warding (13 str 13 con, +1 feat bonus to all defences)

A human can pull the above off by level 11 I believe. Starting stats needed if you bump nothing:
Str 12
Con 12
Dex 14
Wis 14

A naive array that gets this (with 11 being con)
16;14;14;12;11;8
But we can be more efficient by spending our stat-ups on a 14:
16(+2);14;13;13;12;8

Level 1:
12 Str
13 Con
13 Dex
18 Int
14 Wis
8 Cha

Level 4: +1 Int, +1 Con
Level 8: +1 Int, +1 Dex
Level 11: +1 all

Level 11 stats:
13 Str
15 Con
15 Dex
21 Int
15 Wis
9 Cha

Equipment:
Glaive (Polearm, Heavy blade) of whatever kind (I like challenge-seeking)
Rushing Cleats (increase your slides by 1 square)
Armor and Neck to taste.

... and sadly, it still doesn't work. You run out of retrains to do everything you want at level 11 (that is the first level you can MC fighter, and you want Greater Swordmage Warding, MC Fighter, Polearm Momentum, Arcane Admixture and Resounding Thunder all at that level).

So level 10:
Expertise (weapon of choice)
Hybrid Talent (Swordmage Warding)
Hafted Defence (+1 AC/Reflex with Glaive)
Mark of Storm (slide 1 when you hit with thunder power)
Improved Swordmage Warding (+1 AC in Leather)
2 other feats of choice.

Level 11:
Arcane Admixture (thunder) on Sword Burst
Retrain (other feat) to Resounding Thunder (thunder powers gain 1 radius 13 con)

Your swordburst is now burst 2, and slides the target 2 squares.

Level 12:
Battle Awareness (fighter MC, encounter interrupt power 13 str 13 wis)
Retrain (other feat) to Polearm Momentum (fighter, 15 dex 15 wis, push prone if you do 2 squares of forced movement)

You now knock prone on a hit with your burst-2 swordburst.

Level 13:
Retrain (Improved Swordmage Warding) to (Greater Swordmage Warding)

Level 14:
???