@Chaosmancer
Going back to the idea that Fighter gains a special magic item as a high level class feature ...
If your objection is, you want the Fighter oneself to be more mythic, then I agree. A legendary warrior should be able to do legendary things, despite being overtly magical.
The use of a magic item for a class feature is for those players who want the Fighter oneself to be nonmagic, even when using a magic item, such as a magic sword, feels fine to many of these players.
To resolve the conflict between the players who dont want personal magic flavor versus the players who do want personal legendary warrior magic, there is a solution.
When the Fighter player chooses the default special magic item, the player can instead choose an other magic item, and also can decide that the Fighter innately becomes the magic power of the item instead of having an item.