It has a 3-refresh catch. That's how much refresh you need to get immunity to magic. Even better, only 1 refresh if you do it via a magic-repelling item of power.
In addition, he has to aim his attacks using a skill, usually discipline. So he attacks at +5. Someone with supernatural speed, acrobat, and athletics 5 is going to dodge 80 times out of 81.
Third, a block of 10 is strong but not THAT strong. Someone with a true-strike weapon (or just true strike as a power) and a stunt for +1 to attacks, could well attack at +7. All it would take would be a good enough roll to break through the block - or spending a fate point.
Fourth, someone with "All Creatures Are Equal" could ignore his defenses.
Fifth, a submerged wizard that focuses on controlled blasting can attack at +12, with weapon 7. He pretty much blasts through his blocks, easy. Sorcerors are even worse and someone with Sponsored Magic with lots of upgrades can be ugly.
Sixth, a thaumaturgist focusing on enchanting his weapons, armor and items by applying aspects via ritual magic, could attack and defend at higher than +10.
So yeah, he is on the upper 25% of power - in physical combat. That does not make him an "I Win" build in those cases. And it does not take into account Social Combat, Mental Combat, Utility, Investigation where his enchanted items do not offer anything useful.