Here are a fes ways I found online to get Wings to Discovery. They are:
Easy Wings To Discovery (1): To get 60 Wings To Discovery without bribing Malabro or Great Malabro, first capture all the monsters in Mt. Gagazet. Then, capture all the monsters in the Calm Lands. Go to the Monster Arena Trainer and talk to him once. Do not fight the arena creation. A chest containing Yuna's best weapon will drop down . Open it, then talk to the trainer again. Do not fight the arena creation. He will give you some items. Talk to him again for the 60 Wings To Discovery. If he does not give it to you, keep talking to him until he does.
Easy Wings To Discovery (2): Capture about four of each Water Fiend in Gagazet then go talk to the Monster Arena Trainer. He will have made a monster. You have to fight it underwater. It has 2,000,000 health and if you overkill it, you get two Wings To Discovery.
Easy Wings To Discovery (3): To get many Wings To Discovery, bribe a Malboro for 300,001 gil. You will get two to four of them. If the Malboro does not leave, then continue bribing for 1000 gil each time. It should then go away.
Good Luck!