To dive bomb u have to sprint fly then turn downwards, and you will go very fast. When you hit the ground, it will deal damadge (and knock back) to creatures near you. While diving, you can pull up so you are flying forwards, and it will give you a glide. This has and insane amount of speed packed into it, allowing you to persue and escape enemies, or travel across the map fast. If you are gliding and you do the regular attack (RT on Xbox) it does much more damadge. Using this attack, you can swoop to your enemies, use the attack, and then swoop away, all in probably 2 or 3 seconds. I would definitely recommend the griffin as after you get the hang of it you can master the skies, not to mention it can hold an extra person on its back to protect the rear. And it doesent require a saddle.
imo these are the BEST flying mounts in the game because you can hold 2 people and shoot of of its back along with their maneuverability, speed, damage output, stamina, dive bomb, 2 special attacks, and health. I'm currently leveling up my griffin and so far it has 500% damage, 1500 stamina, and 15k health and there is practically nothing that can take it down. (also, its dive bomb swipe attack does over 1000 damage!)