Quote Originally Posted by Rubedo
Only FFX has break Hp Limit Weapons/Armor... Well, unless there are some in different games that I haven't heard of.
Technically, some of the moves in FFVIII have a "break damage limit." Kamikazi and Eden are two examples (maximum of 60,000 points of damage if the enemy is in 'Meltdown' status), but that's not HP or MP...

However, in FFVII, no, there is no way to 'break' the max HP limit, and as everyone else has mentioned, the HP<->MP materia will break the max MP limit into whatever the equipping character's max HP is. Put simply, it just switches the max HP and the max MP with each other.