Like the title says allow bravery incrementation, and/or award (even partial), for playing underlevel. So you do a level 8 quest where no one is above 6 then you would get Elite Bravery.
It seems to me Bravery encourages the opposite where players wait until 10 to hit that level 8 quest, and this would reward taking a risk. Some of the most challenging questing I did was PUG'ing out for VoN flagging on Elite and having an entire group not only below the elite level, but some below the quest level as well.