am i the only one that has problems leveling maria up??

[DarkLadyNyara]

The ones in the back row can't get hit by physical attacks unless the characters on the front row die.

Actually, they can.
Some enemies use flashy physical attacks that even hit chars in the back row, and arrows probably count as physical attacks too.
However, you ARE covered from most physical attacks, that's true.

Arrows fall into a different category. Remember, bows can be used from the back row too. If it uses MP (and arrows do) I don't consider it a physical attack.