My opinion on the items:
Shieldstaff: Doesnt do anything insane, but is pretty cool overall, every wizard would be happy to have it.
Mace of Midday sun: While the radiant damage on hit is definetly usefull, I don´t like "win more" abilities, especially if they only trigger in about 1 out of 20 attacks.
Manacalon Javelin: As someone already pointed out, while this does give a dex bonus, it can not be wielded with dex. Having a bonus on dexterity is still pretty cool as a str-fighter though. Also, it always returning after you throw it basically makes your character ranged.
Mountain Breaker: The strength bonus is (if its +2 as I assume) basically a better version of a +1 weapon. Casting thunderwave 1 per long rest (even so its centered on yourself, I´m just going to assume that it wont HIT yourself) sounds pretty cool for a weapon if you get it early, if you get this later in the game it will probably be only for some niche-situations (because the damage doesnt scale; the fact that you should only use it with alot of enemies and no allies around; and constitution saves usually being pretty good for higher level monsters).
Winged Dagger: Casting feather fall once per long rest might not be huge, but it just makes me feel save to know that I can if something happens. Being able to misty step once per long rest can give that spike of mobility you need to reach your target, and also can be quite interesting out of combat (although this item being a dagger makes it interesting for rogues, who are already able to dash as a bonus action, so I wonder if it makes more sense on a fighter, even if you dont attack with it)
Rating them after a combination of usefulness and general flair (even so it was really close between first and second place) I´d rate them:
1. Winged Dagger
2. Arcane Shieldstaff
3. Manacalon Javelin
4. Mountain Breaker
5. Mace of Midday Sun