That is perfect in my view. When it is first released, let everyone reassign their skill points one time for free however they like. Then, going forward, let people reassign all their skill points for 50 gold, like changing your nation flag or game name. A 50-gold purchase would set all allocations to 0 and put all your skill points back in "available skill points" to be distributed.
edit - simply making the attack and def points suddenly valuable in the game doesn't solve it, because then you'll have the other side very upset for having all their points stuck in energy. However, if the game allows for re-allocation, then changing the usefulness of the different skills in game would have less negative impact.