Go to Versus mode and choose a private match. Set the bots number to the maximum. Make sure the score limit is maxed out so that you have the most possible time in a match. Also, set the difficulty to Casual. You can now work on whatever medal you are trying to achieve. Also, when choosing a level, you can switch out which weapons you want. For example, if you change them all to Torque Bows you can use that the entire match until you have enough kills with it to unlock its execution. You can keep switching the guns desired before you start a new match and work with them to actually unlock all the executions. Note: The only weapon you cannot choose is the cleaver; for this, go to Horde mode and choose Drydock. Tthe Butchers will appear on level 2, and from there you can pick up their cleaver and use it until you have unlocked its execution. By using this method you can unlock many medals.