Let's make one thing absolutely damn clear: when a ship is attacked in open international waters they have the right to defend themselves with whatever means they have. So even if we fully accept the Israeli version that their commandos were attacked with metal bars, chairs and even handguns taken from the commandos, this was absolutely legal. In fact, the people aboard these ships had the right to use assault rifles, mortars, heavy machine guns and even anti-air missiles. We know that they had none of these, as the ships were searched by the Turkish customs authorities, and the ships were even X-rayed. But even if the crew and passengers of the Mavi Marmara had killed every single attacker who attempted to board their ship they would have been in their right.
Israel has no jurisdiction on the high seas whatsoever and its propaganda about having the right to enforce the blockade even in international waters is utter nonsense. The illegitimate use of force to seize a ship and kidnap is occupants is simply an act of international piracy. Piracy can, and should, be resisted with all means necessary.