Nahh. The smart play is to forget about warmage and go with sorcerer or wizard. Caliban has given the basic overview of the problem with a warmage, but I'll approach it from a different angle.
Warmages are not fighter mages and have little if any synergy with the fighting classes. What warmages are is sorcerers whose spell-list is basically the evocation list plus a few others. Now, that's well and good if you want to play a mage who blows things up with balls of fire or orbs of acid, but if you're doing that, you're not getting any use out of the four fighter levels. They don't increase your DCs. They don't give you better spells. They don't give you more spells. In fact, unless you take practiced spellcaster, they make your spells do less damage.
If you're going to take 4 fighter levels, without suffering a net decrease in power, you need to get some things that are as good as four caster levels and two levels higher spells. What kind of stuff can make up for that?
Well, the fighter levels give you some hit points, more base attack, weapon and armor proficiencies, and qualify you for spellsword and eldritch knight. You also get weapon specialization and a number of feats. You'll notice that all of those things make you better at fighting and do nothing for your spellcasting ability. So, if you're comparing yourself to a mage, you'll always look worse.
But what if you compare yourself to a fighter? You want to be a badass with your swords. Well, you're giving up at least two points of base attack (2 points if you go Ftr 4/Sor 4/Spellsword 3 (Complete Warrior)/Eldritch Knight the rest; it's 3 points if you go Ftr 4/Sor 6/Eldritch Knight), a bunch of hit points, and feats. What you get out of that has to be worth it. So what do your spells give you.
If you're a warmage, you get (IIRC) true strike, fist of stone (lvl 1), whirling blade (lvl 2), blades of fire (lvl 2), and fire shield (lvl 3), and that's about it. The various orb spells can substitute for a bow and you get a few other options but not many.
If you're a sorcerer, on the other hand, you've got a lot more to play with:
1. shield (get decent AC even when wielding a two-handed weapon
true strike (good synergy with power attack and combat expertise)
ray of enfeeblement (good defense and great synergy with improved trip)
fist of stone
critical strike (complete adventurer--swift spell doubles threat range and gives you 1d6 sneak attack for one round)
swift expeditious retreat (CV swift spell, +30 speed for 1 round)
protection from evil
2. wraithstrike (CV swift spell--all attacks are touch attacks for one round--great synergy with power attack, combat expertise, Arcane Strike, and whirling blade)
Alter Self (I know you said you don't want to shapechange but it's a good ability)
Swift Fly (fly at 60 for one round as a swift spell)
See Invisible (invisible foes are the bane of fighters without a way to see them)
false life (get more hit points)
darkvision
blur (OK, I think the spell sucks, but some people like it)
3. heroism (+2 to hit, saves, and skills)
magic circle vs. evil (+2 to AC and saves vs. evil, immunity to druids--oops, I mean non-good summoned creatures)
greater magic weapon (buff your weapons)
keen edge (buff your weapons)
fly (flying foes are also a pain for melee fighters)
displacement
blink (good defense and an offensive bonus (denies foes dexterity and gives +2 atk) as well as marginal utility)
haste (buff yourself and your party)
4. Greater invisibility
stoneskin
fire shield (not as good as you might think because usually you want to avoid getting hit and fire shield only works if they hit)
dimension door (good for grappling and escaping)
anticipate teleportation (because who likes being scried and fried)
polymorph (become the monsters you fight--even though you don't want to)
As you can see, there's a lot on the sor/wiz list that synergizes very nicely with the abilities of a melee fighter. The warmage list doesn't have most of those spells.
A warmage/fighter will, for the most part be an inferior warmage who is casting fireball when normal warmages are casting empowered fireballs or an inferior fighter who is swinging twice for 1d8+6 when real fighters are swinging three times for 1d8+9 at a higher attack bonus. A fighter/sorcerer, on the other hand, can use more of his magic to make himself fight better.
Felon said:
Hmm. I'm actually thinking the smart play now is to take a warmage level at 3rd and grab Practiced Spellcaster then. Then maybe Battle Caster at 6th. Too many options too early, not enough later. Ain't that always the way?