Ooo, good questions! Fun questions!
Patrol is definitely the easier job to get in Wellwood. Pretty much all they need to do is show they can fly a patrol route and report anything out of the ordinary they might see while they’re out. This includes odd behavior from animals (including non-predators), bad weather approaching, damage to the forest, and potential dangers moving closer. This way a proper course of action can be planned out before something is right at the village. If the area needs extra help from the sprites, they can figure out who needs to go on an expedition (for example, setting up a group to go and help some sick trees).
Becoming a knight is a bit more involved. They have to be training all the time, and ready at the drop of a leaf to rush out in defense of the village. It’s not a job for the lax. In a pacifist society, the knights also have to accept that they will likely end up hurting something to defend the village. Not everyone has the mental fortitude to do that, especially when there’s not really an option to hold back.
If they have the right drive for it, though, the knight(s) in charge will take them onto the team, and oversee their training. They get practice weapons until they’re proficient with the movements they need, and if they impress the bosses then they can earn a sword of their own out of the armory. Then, they’re a knight dedicated to protecting the village, no matter what it takes.