Well pro has already forfeited round two so I don"t have much to rebuttal but well go on explain how the Arbiter aka Thel Vadum formerly Thel Vadumee. Thel Vadum was a former fleet master of the Fleet of Particular Justice something not easily achieved. Thel has lead 50 ships and has devastated the human systems he has fought against and even went on the ground attacks when launched unlike many fleet commanders showing his will to fight. When encountering the planet Camer a vital planet for producing materials for the UNSC Thel performed a slip space jump well within the human system and penetrating the early warning system before the UNSC could react engaging the planet before they knew what was going on leading the loss of the planet with minimal damage to Thel"s fleet. Thel later went on and lead the invasion force on the planet Reach human"s last world before Earth and Humanity"s military hub and ended with the destruction of Reach and most of the UNSC"s ships and military force. Vadum has been attributed to over one billion human casualties and the loss of at least seven human planets, his forces has defeated all UNSC counter attack at the cost of 123 fleet vessels and 23,000 personal and with the later loss of reach ONI has predicted a 0% chance of victory through traditional means fighting Vadum. And we can later see when Vadum becomes the arbiter he is sent thought many suicidal missions and has come out alive and victorious and has lead the humanity to victory against the covadent and without his help and his ships/ connections the humans would have been whipped out with the firing of the halo rings when the prophets would remotely fire them through the lesser arc. That is all I have for now I wait for pros response.
Sources: Halo 2 anniversary terminals