Hello and welcome to the sub. I'm Bostonfan and I'm gonna try to help clean this up a little bit so when the mods take a look at it, you can get approved faster. Hopefully I don't have too much information here so that you're scared by it, but there is a lot.
So lets start off with your numbers. Your numbers look fine for the most part, there are just a couple issues that I have with some of them. I'm going to start off with your composure 1. Composure 1 means that your character will run away from literally anything. A butterfly lands on his arm? He's out. An opponent draws a gun? Alex is on the ground due to passing out from fright. This doesn't really work for a hunter and I'm going to recommend that you change this just to make it a little easier on yourself unless you are absolutely sure you can handle this. It's more difficult than it seems and I don't want you to hate your character because of it.
Besides this one issue, I see that you have Drive 2, but I see no reason for you to have it in your backstory. If you want to keep this, I recommend that you at least include something about it in your backstory.
Holy crap that list of flaws. Uh... you have a lot of them. Most of them fit somewhat decently into your character, although there are a few issues I see with it. First off obsession can just be compulsion. They're the same thing in the context you're using it in. Your painful semblance needs numbers attached to it. How much damage does it do is the main thing that you need to address. The last thing number wise is your Sadist flaw. This flaw is generally frowned upon for the reasons that Baz gave you. It's overly edgey and most characters that take it kinda bomb the character and it doesn't really turn out well. I'm going to advise you to not take it as it's something that puts a lot of people off, but if TRULY think that you can use it and execute it well, then I don't see an issue with you having it. That said, I'm not a mod so you really don't have to ditch it, but this is just something I'm advising you to do as a fellow RPer.
Moving on to your Physical Description, it feels pretty bland. The only things that stick out really are the Grimm designs that you have implemented, and even then it doesn't really stand out. The point of you character being in the world of RWBY is to make him/her pop and do things that wouldn't make sense in a normal context. Don't be afraid to go overboard on your character design if it means that your character is special. Make your character stand out from the rest of the students that fill the background. A white t-shirt, overcoat and jeans is something that a background character would wear, make your character worthy of the spotlight. This is my favorite section to do for my characters, so if you need any help don't be afraid to contact me. I can help you work on something if you want.
So the Weapon is probably the section of the character that gets the least amount of love for how important it is and its something that we're picking up the rules for. One of the biggest rules of RWBY is that 'its also a gun' and your weapon isn't a gun. Besides it not being a gun, I don't get a RWBY vibe from it. From what I can tell, it's just a mace/polearm with heads that spin. I highly encourage you to add more to this weapon and give it a ranged form that is reliable and can be used in battle. Much like the physical description, you want to make your weapon different and special. Something that nobody else has.
As I said earlier, your semblance needs numbers attached to it. How much of an AoE does the ability have? How does it do damage? How much damage do you take from your painful semblance flaw? These all need to be addressed for getting your character accepted. I'm not too good with numbers as far as semblances go, but here's what I would do.
Aftershock: Alex releases a violent kinetic burst around his body equal to semblance x 3 yards that pushes people away from him if they pass a strength check against his semblance. If the check fails, the target does not fall over and takes no damage. If the check succeeds, the target is knocked over by the number of successes from the roll in yards and rolls twice the successes for damage. Alex also takes damage equal to 1/2 semblance rounded up upon activation.
Costs 2 Aura points.
To simplify this, if you use it and Alex succeeds in the check with two successes, the target is knocked back two yards and takes up to 4 damage, but Alex takes 2 damage. If Alex fails the check, the target is left alone but Alex still takes damage. I'm going to summon /u/thebaz11 to see if this works. If it does you're fine to plug it in, if not I'm sure you can work with this.
Moving on to the Backstory. This is my second least favorite area, but its also one of the most important. Taking a look at it I'll try to give you my thoughts on it.
You start off strong here. Establishing his background as well as his parents and how he interacts with them right off the bat is nice. The only thing I would like to see from this first paragraph is who he war raised by. You say that his parents weren't around much and he was homeschooled. I'm assuming that that means he had a nanny or something, but I think that that is just something you should acknowledge.
Moving on to the second paragraph, I'm left with a couple questions before I even start reading. What happened in the time that was skipped here? How did he develop school wise, socially, mentally? Did his relationship with his parents change at all? Did he make any friends? I'd just like to see something acknowledging that his life changed during this time period. Now then, as far as the actual paragraph. I don't like what happens here, but if that's how you want your character to work that's fine. It's pretty cliche and overdone at this point, but what isn't anymore? He goes on a trip with his parents and they get attacked by Grimm. His parents die and he is saved by hunters. I believe that there is a way that you can have this type of development without the seemingly needless angst and edge, but this is your character so if you feel that this is how you want to do it, I can't really stop you.
From here, the backstory looks pretty solid and I don't really have any issues with it until he runs away. Does he not have any other family members or family friends that he can go and live with after his Aunt? Running away would be the last thing that anyone would want to do, especially someone with his name that would be recognized and potentially have issues with. I think that there are other options here that you didn't explore so you could do what you wanted, which is fine, but it seems a little forced to me. The only other major issue I have with the backstory is that a group of street thugs are scared away by a couple of librarians? That doesn't make much sense to me as there are many street thugs in the group who are probably armed but only two librarians who most likely not armed... This doesn't make much sense to me but if you can provide a reason as to why they'd be scared, I'll let you do you.
From here out it's pretty standard except you forgot to mention where/how he gets his huntsman training. I'm assuming that he goes to Signal due to his location in Vale, but I'm not fully sure. The whole bullied thing seems pretty out of nowhere but I can see how it would work. You give his reason for going to Beacon, which is something that a lot of people miss.
And finally, the personality. This is my least favorite section as I'm not too good at forming the words and describing what I'm thinking, but I'll do my best to critique yours.
You give him the standard 'quite and lonely' personality that characters of this nature come with. He's quiet and likes to keep to himself but he can talk a lot about what he likes and he's a rule breaker when he wants to be. That's pretty much all that I'm seeing from your character here. Everything else in your personality section seems to be describing his flaws and how he's affected by them. I'd like to see some expansion on who he is and how he interacts with people in different situations and especially in combat with his Composure 1, if you choose to keep it. This section probably needs the most work out of your whole sheet and it's also incredibly important to who your character is.
That's all that I have for the first part of the critique, hope I didn't drown you in information. I know that there is a lot here but if you take it one step at a time, it's not that bad. If you need any clarification on what I've said, just let me know and I'll do my best to clear it up. Wait for Baz before doing anything with the semblance I gave you as he'll be able to tell you if its good or not.
With that said, welcome to the sub and I can't wait to see you get approved!