in the bottom you can see a bar, there is theoretically no levels in the game, since that bar can be filled an infinite amount of times, every time you fill 1/3 of the bar you get an ability point and every time you fill a whole bar you get a skill point, as levels go up you need more skillpoints and ability points to increase your stats and get more abilities and quests starts to fill the bar more times.
all of the boxes have 7 skills. you need to complete the inner box for assault rifle to get the outer ones which are more abilities (who are all really cool tbh) but the abilities cost more and more, so the inner ones cost 1 or 2 AP (ability points) but the first in the outer rings starts to cost 24. 27. 31 and so on, making them expensive.
these requires SP (skill points) every weapon have a dps function and a secondary function and you can increase the stats in either one, after what fits your playstyle. but as you can see they get more and more expensive, first 1 SP, then 2 SP, 3 Sp and so on so forth.
you can see this dude have 6 points in his blood magic, so he can use up to tier 6 blood magic weapons (which is pretty high) but on the other hand he doesnt have alot in the other types, like blade where he can only use up to tier 4 blades, there are 3 equipment types in the game Head, major talisman and minor talisman, the leveling system for those works the same way.