The fifth Repeatable Militia Side Quest you can get is given to you by Jack the Fisherman who can be found on a bridge overlooking the water in Vesper.
Jack asks you to slay some Harpies. This is a great quest to get some Feathers while you hunt.
The best place to hunt for Harpies is in the dungeon of Covetous. This quest accepts the Dazzled Harpies along with the normal harpies, so you can run into the void pool to get a bunch of normal harpies, and kill the dazzled harpies on level 1 as well.
Now that you have killed the 100 harpies, collect your 2500 Gold and 3600 Experience Points daily!