What the new Arena quest section is: A set of 4 quests that require a total of 4 arena victories and KO 20 10+ foes.
- Win 1 Arena Battle - Rewards a Dueling Swords
- Win 2 Arena Battle - Rewards 100 Feathers
- Win 4 Arena Battle - Rewards 100 Feathers
- KO 20 Level 10+ foes - Rewards 1 Orb
With a Arena season taking 7 days, this yields another 1400 feathers and 7 orbs. I'm guessing that this is a fairly significant boost to feathers for quite a few people, especially if you can't get a Bonus Hero in your Arena team. Probably halves the time it'll take to get a bundle of 20K feathers.