What this clause means is what it says. What it says is that nothing in this act, whether by mention or omission, affects in any way Parliament's power to implement legislation in respect of the agreement or related agreements, or to fulfill obligations that these agreements prescribe. It does not cover breaches of, or derogations from, obligations in those agreements. It simply doesn't address that. It is there for certainty, as a matter of construction, so that it is clear that Parliament has the authority to implement legislation to give effect to the agreement and the related agreements. The related agreements are the ones defined in the legislation.
On June 1st, 2010. See this statement in context.