Told OP it was a bad idea, was ignored by OP in the Blackcoin thread. If you don't understand the code you're modifying, don't muck with it.
These attacks are not applicable to BlackCoin. Guess why.
My guess is that you modified the trust weighting for PoS blocks (to lessen weighting for any individual block based on coinage) or that you manipulated timestamping variability, neither of which are great solutions in the distributed system you're playing with.