Giving martials more than one reaction per turn

i have always think of giving full martials ( barbarian, fighter, monk, rogue) extra reactions a tier a the end of tier 2 and begining of tier 3, but making then conditional, so say fighter and barbarian at level 10 get an extra reaction that can only be use for op OA, monk and rogue can only used theirs for deflect attacks and uncanny dodge, i dont know if this is actually good or not, so i want to read what your think and what would you do instead if you think is meh? would you lower the level? give more reaction at higher levels? something quick, simple an useful for martials