Go into the "Way of the Warrior" state and stealth attack both enemies. Repeat these actions until both enemies split in half. As a bonus, you will get the strongest bow in the game before the fight begins.
At the start of the ambush, attack Conrad with an arrow which will daze him. Then, take out his ground soldiers. Attack Conrad with your arrows until he falls to the ground you are standing on. Conrad can can hit you from any point with his detonators at long-range distance. Keep moving while you are in open areas and do not try to fight him hand to hand; he will always block your attack. To defeat him, hide in the tall grass areas and wait for him to get close enough for you to do a stealth attack and a series of actions involved with the stealth attack.
While behind Sean Wallen's chopper, attack it with arrows until it glides behind you. While in front of Sean Wallen's chopper, avoid all of its attacks until the "B button" action appears on the screen. To defeat the chopper, press B when prompted and complete all of the actions involving the Wiimote and Nunchuk.