It is nowhere in Peter's intentions to make the first strike, but he feels rather certain that Edmund will based on his disposition thus far. Rhindon is an old friend, his oldest remaining one in fact apart from his siblings and the great lion himself. The loyalty of a hilt that seems to complement the natural curl of calloused fingers is not lost on him for a second; the advantage it gives him is invaluable.

"You said you would take what you want."

So go ahead.

Despite his instructions to Rosella to the tune of not provoking his brother, Peter veils nothing about his tone. The point of his suggestion to Rosella was largely preventative.