If that breaks your suspension of disbelief, then you clearly didn't grow up watching Dragonball Z like I did.
Unless you are talking about 4E, Fighters have a long way to go before they need to worry about being overpowered. I mean, 3E's Warblade and other Tome of Battle classes are undoubtably vastly more powerful than a standard 3E fighter, but they were hardly overpowered. They were still significantly weaker than the 3E Wizard, Druid, and Cleric, after all. They actually sat right in the spot I'd call "appropriately powerful." The Fighter needs some pretty potent stuff in order to stay balanced. I'd say that both the Warblade and the 4E fighter made a lot of sense without any overtly supernatural abilities, too. I don't think you have much reason to have those worries.
I grew up watching Star Trek and the Time Tunnel. And My Mother the Car. Which is most likely why I don't have any issue with sentient items.

I am not going to disagree that the fighter needs improvement but as you pointed out it is not just the wizard but the cleric, druid and I am going to add rogue. Once a rogue has a decent use magic item they can use spells that make them more effective in combat and with their sneak attack sometimes do more damage than the fighter.
I think most of what the OP wrote is pretty awesome I just had an issue with the spell thing and the dragon.