OK so I am going to be pretty critical here and although that might not be 100% fair because you clearly don't know how we do things here I do think it's the most efficient way to help you improve.
Occupation: Just leave it as 'First Year Beacon' maybe plus and side job they do. You won't be able to edit the profile without our permission so it will just save time when Yin inevitable finds a team.
Appearance: So silver eyes aren't going to give you any additional abilities they will just be purely aesthetic. You also might want to put in a little about school uniform as well as something about what he sounds like, how he holds himself, ect, ect.
History: So this really doesn't make sense. He runs away from an orphanage at 8 and some time later, before 16, be basically gets forced into an underground slave arena. OK not impossible but why is he getting paid if he doesn't want to fight? Unless of course he does want to fight but that is another whole host of issues. How does he buy anything if he is again you know a basically a slave and why do they let him buy still which might lead to his escape? If these fights are to the death how does Yin survive long enough to learn how to fight. And what kind of people is Yin winning against and killing, he doesn't have his aura at the time so they would have to be other children, like I wouldn't want that at my school.
Personality: OK so let me get this straight, Yin is abandoned by his parents, beaten by the others in his orphanage and then spends half his life as a slave pit fighter but has no negative emotional trauma. I get that you might not want to play an edge lord, although if that is really the case I would recommend not giving Yin a backstory which makes Batman villains look like they got adopted by the pope, but it is simply unrealistic. You have a section on how Yin got named 'The Grimm Mamba' for his ferocity and amount of people he had killed but that has no affect on him personally? I'm sorry but this is blatantly a Mary Sue. Being a Faunus you should also mention here how he deals with racial abuse or the like as well as opinions on the White Fang.
Semblance: So if you look back at the show you can see that everyone's semblance, except for the schnees, is one ability. Super speed, increased strength and increase durability would all be perfectly fine semblances on their own. Having all of them is ridiculous.
Combat Behaviour: We want you to have at least 2-3 weaknesses inbuilt into this section. You could also add more detail on how Yin deals with different weapon types. RWBY has a lot of fighting in it so try to make this section as detailed as possible.
Weapons are fine.
I know I've been pretty harsh but if you would like any help please feel free to message me, talk on the discord, or here. Either myself or someone else will be happy to help you iron out this character. (Discord link
https://discord.gg/Es2GCj4, remember to use the same username)