[Sheya]

Well Im sure Star gonna post soon... but Ill give a go at it haha.
You build is your and yours alone but some of those weakness you were asking for are as follows:
Minimum hp/def/blockrate
Minimum damage as far as single hits....
Yes the extra sp and magic defense is nice but mainly fighters arent tanking magic dealers. They are usually chasing them if anything or running. Because of the lack of either one of these other traits your gonna have difficult time tanking multiple mobs in higher lvls and probably gonna be stuck soloing a lot. Unless you enhance your armor and/or buy stated armor.
There is more but Im sure Star will cover it he is good at that.