Talk:Kunai/@comment-4068127-20130810041317/@comment-67.77.67.176-20130810104824

The rank on weapons is your affinity level (with that weapon). The level it's referring to is your mastery level. Up in the top left of your screen in menus you'll see your icon and a bar next to it. Click the bar to see how far you've got until the next mastery level.

Warframe affinity levels give you 200 exp, while weapons give 100 per level.