Add my vote to the "we don't need this" pile. Concentration serves two very specific functions: (1) it limits the number of persistent, powerful effects a caster can keep active at a time, and (2) it discourages getting hit. #1 has no bearing on martial characters, and #2 is bad for a lot of melee characters, most of whom are martial.

If you (royal you in this case) think there's something is wrong with martial characters generally, any fix you write should be targeted to their problems. Hacking an existing subsystem to achieve your goals is just going to add unnecessary complication and deleterious side-effect.