Khan's ultimate relies on line of sight to grab his desired target, pull up Fernando's Shield and block your allies with it. Khan cannot grab any targets behind Fernando's Shield unless he has already fired his ultimate.

Khan has an easier time taking care of other tanks. Use Fernando's charge to reposition yourself if he happens to be dissing on you, and try to protect your teammates from his ultimate by using your shield.

Khan can prevent Fernando from protecting his allies with Commander's Grab. It will cancel his shield and displace Fernando behind Khan, meaning he must waste his Charge ability if he wants to be back in the fight.

Khan can destroy/disrupt fernando shield. Keep shooting Fernando forcing him to throw out his shield then use commanders grab to disrupt it. Even if fernando has max resilient doesnt mean he can escape stun. Equipt Vortex grip for better result