I don't get this at all... this is the way I see it/interpret it:
Targets are adjacent (or within 2 squares) to you - your Avenger uses the power Warding Blade, pushing all but the primary target 2 squares away. Your Avenger had Repulsive Armor up.
Non-primary target attempts to move back into an adjacent square. 2 triggers are at
work here - one is an immediate reaction and one is an immediate interrupt. The IR allows the target to complete its move action before it kicks in and the II takes full effect *before* the target completes its action. So the II hits, then the IR kicks the target one square back out.
And this is a case where a specific rule over-rides a general rule, so if any of the other non-primary targets enter an adjacent square, you get an OA against them as well, (or any that hit or miss) at least until the end of your next turn.
I don't see where the need for reach comes in - Unless you mean if a target with reach 2 hits or misses you? Can you explain further please?
Thanks!
PS But I do love OOTS!