This build pays the heavy feat tax typical for hybrids. When you're finally set, you're already 6th level or something.
Another issue is that you have all these nice area powers like your dragonbreath and the sorcerer blasts, but none of them provides a fighter mark. A dragonborn fighter /
multiclass sorcerer doesn't have these issues. (Think about it: multiclass better than hybrid...)
A third issue is MAD (multi attribute dependency). A Cha 18 does nothing for a fighter, and without Dex, Wis or Con, you're locked out of most good weapon feats, and you you can't benefit from rider effects on any fighter powers. And we're not even talking about the wasted Dragonborn Con bonus to healing surge and the low Dragonbreath damage.
To sum it up: It's not a good build because the
opportunity cost is too high. You're better off with a pure dragonborn fighter who picks up some blasting on the side, or a dragonborn sorcerer toughened up for melee with Sorcerous Blade Channeling, Toughness and AC booster feats.
Well, to go with Fighter MC Sorcerer you need to spend 1 feat to get the multiclass, another feat (at no earlier than 4th level) to get a single Encounter power, another feat (at no earlier than 8th level) to get a single Utility power and another (at no earlier than 10th level) to get a single Daily power. You
do not get an At-Will without Paragon Multiclassing, and the only way to get more than three powers in the second class (from the aforementioned feats) is to PMC or pick a Sorcerer Paragon Path.
So, unless you're MCing for a single Sorc Encounter power, I don't see how Hybrid Sorcerer is any more feat heavy than MC Sorcerer. You also get more options in some respects, since you get to have a Sorc At-Will. Also, you can have these powers at level 1 with no additional feats, whereas you have to wait until level 4 to get your first Sorc Encounter power. So saying that it's not ready until "level 6" is a bit specious, since the MC Sorc will only have
a single encounter power at that level, whereas the Hybrid Sorc will have 1 At-Will, 1 Encounter, 1 Utility and 1 Daily.
As for the MAD issue, this is ridiculous. Unless you're going STR/CON, which sticks you with either Axes or Hammers by default and gives you crappy NAD's (note: My Dragonborn Fighter did this, I'm not saying it's not viable) you're not taking full advantage of the Dragonborn bonuses to Surge HP and Dragonbreath damage anyway. What about a Dragonborn wielding something like a Great Spear? It's a polearm and a spear, meaning you should bump DEX and WIS to get the feats and rider bonuses. Are you saying that this build is completely unviable because it doesn't have high CON?
And as for secondary stats, that's why I suggested pumping up DEX. The OP wanted to have a
swordmaster character, which would mean Heavy Blades. He can get a 14 DEX at level 1 by dropping STR to 16 (which is doable since Heavy Blades like Longswords and Bastard Swords have a +3 proficiency bonus), which would allow him to pick up HBO in Paragon. The only important feat he'd be missing would the Heavy Blade Specialization feat, but he could just use a Jagged Weapon to increase his crit range if need be.
Part of the thing you're ignoring though is that where he loses effectiveness as a Fighter, he gains it as a Sorcerer. If you want to bump the damage on Dragonbreath there are two feats to do so, one which allows you to pick the attack/damage stat (so you can switch it to STR or CHA) and another that allows you to make it an Arcane Power for purposes of bonuses. The latter is waaaay superior, since now you can add in implement enhancement bonuses to attack and damage, as well as use your extra Sorcerer damage. You know, the one that the MC Sorcerers don't get except for once per encounter.

(Although, to be fair, you can PMC and pick up the extra feat to get it added for all Arcane powers, and get a bigger bonus)
Fact is, there is no
BEST way to do these things. With each choice there are different pros and cons. If you just want a Fighter with a single Encounter blast attack, then yeah, MC Sorc and pick up that blast. If, however, you want a Fighter that is equally at home wielding dangerous weaponry as he is wielding dangerous elemental magics, then hybrid is the better choice because you get more access to powers and class features needed to use them effectively.
Also, note that in my original build suggestion, I only had two feats listed that were needed to get your character up to "effective" levels. One was the feat that let you use Heavy Blades as implements, and the other was the Hybrid Talent feat that grants access to the Fighter's Armor Proficiency list. You would basically be fine with just those two feats, you hardly need anything else to be honest. Other things like Versatile Expertise would've been taken anyway, regardless of whether you single class, multiclass or go hybrid. And things like Fighter Weapon Talent are by no means
critical to the build, and could easily be skipped in favor of a better feat (like the aforementioned Versatile Expertise, which beats out FWT for this build if you're looking at an either-or scenario). This is hardly a feat intensive build....