I could see moving Reckoning into the Retribution Tree as a realistic consideration, but with one of two catches.
1. Make Reckoning like the Death Knight's Necrosis ability, but instead of Shadow Damage, Auto Swing deals Holy Damage.
OR
2. Make Reckoning a three point talent and have it have a 5/10/15 or 10/20/30 or 15/30/45 percent chance that Crusader Strike will immediately cause you to hit your current target with another Crusader Strike(?).
I don't really like the idea of the chance of your 4 attacks having an additional attack in 8 seconds, cause you will only be swinging your weapon 2 Times.....3 Times TOPS (you would need an EXTREME amount or Haste)!