I follow Lv80 cap and skills name is based KR (English translation).
Type A (Sonic Slash) (Better in 1vs1)
Type B (One Flash) (Better in team matches)
In Type B, there are much SPs left which can be used for PvE skill > Hybrid build
This explanation is focused to Type A.
It's a good skill for BM, but it is only good when used in awakening. Take this skill isn't bad decision but it can be skipped. Don't forget about the skill note if you plan to take it.
It's must have skill for all Ravens. Although Lv1 is enough, but there is a different when this skill leveled up. Dumb the left SPs here. Skill note is preference.
It's super armor is good, but it has bad startup time. And it is MATK damage skill instead PATK.
This skill is work as utility skill. Insted of just for send your opponent away, this skill can be used for catch also, if you know how. BR will works well, only if you have high attack speed. Faster, better.
If you want to take Earth Break, you must have the skill note. For catching, the main problem is : when the stun doesn't proc, Is that just waste of MP? Yeah, that's true. And it's a bad thing in team matches. For mid-combo use, there are some ways, like use it in awakening after high launch (ZZXX or other). It seems Earth Break has some weakness, let's see it's alternative..
This skill has larger hitbox than animation, it can hit opponent below platforms also. Ground Impact is usually used as hit-confirming before starting combo. And it's not bad skill for catch, thanks to it's 360 degree large hitbox. Skill note is optional. If you asked why I leave it Lv1, Ground Impact is MATK damage skill. And leveling up isn't increase a lot damage, magic isn't BM power.
A populer skill right now, it seems. It's damage isn't high and it costs 50 MP to use. With the skill note, it will 100% critical, so that is good if you have high Add. Damage. But, Megadrill Break doesn't have super armor and no debuff from it. No super armor means risky to use in team matches, no debuff isn't a problem. It's better to use the SPs for other skills.
Before PvP S3, I take this skill because it looks interesting. But now, I skip it. The reason is I take Sonic Slash. Maximum Cannon is good actually, but it is danger if you miss. So, if you take this skill, don't spam it a lot as I do.
Lv1 is enough for fast-wakeup. But if you need some accuracy boost, you can leveling up this skill. Master it isn't necessary, BM has little accuracy from Exquisite Swordsmanship.
Cannon Blade & Seven Burst
Magic isn't Blade Master power. Cannon Blade is good actually. It isn't worth to take Seven Burst for PvP.
A high damage skill with the skill note, it seems this skill is main dealing damage for BM. There are some ways to prevent your opponent knocked down, but most of them needs awakening. Just like Earth Break, use it after launch; Use it when your opponent behind you in the mid-air; or use it when your opponent close to ledge.
Basic Strenght Training
Master for some extra PATK and DEF.
Leg wound debuff from this skill is really good, Cut Tendon is must-have skill for PvP. With the skill note, it will prolog wound debuff. Leg wound debuff is really annoying at PvP. There are a lot combos which needs dash or air dash, combo or skill canceling usually needs dash, and steeping and movement is very limited. So then, master this skill.
Master for longer combo. Thanks to new level cap, now you can feel the S1 Lv5 Infinity Cause.
Shockwave - Devider & Cutter
If you want to take Shockwave, original (Devider) version is better. But, do these skills worth taking for PvP? Their total damage isn't high and they do magic damage instead physic. Although they're not really that bad for team matches, but skip these skills is better.
It's only give a little critical boost, skip it.
This passive gives attack speed and accuracy boost. It doesn't gives a lot of them but attack speed boost is good.
A good skill if used without awakening to multi-target. For PvP, Hypersonic Stab isn't needed.
Not bad skill for PvP. Buff given from this skill is good. Recovers your HP and add 5 seconds Leg Wound debuf to your opponent. Higher level, higher HP recover. It is still worth taken for team matches, but skip it is better I think.
If maxed, this skill can deals a good damage for active skill. And take a look my build, Shadow Piercing will be main dealing damage for active skill. Of course, you'll need the skill note to be any good.
Deadly skill for team matches. It's the only BM special active with mid-range catch ability. Wolf Fang is must-have skill for Blade Master. Try to spam it in team matches, especially at small map (like Wally's Castle Rooftop). But please, consider your team-mates too.
Intermediate Strenght Training
Max for higher damage.
I like this skill for both PvP and PvE. This skill is may be bad in terms of damage and goodness, but it is still nice in team matches for burst damage. It works for mid-combo use only. One Flash isn't reliable for catch, this skill is lag-sensitive. It's easier to change your position with One Flash than V-Step. This time I wanted to tried Sonic Slash again..
Lv1 is enough for catch utility only. This skill has super armor, so it is safe-catch skill. If your catch fail, just use Burning Rush and you safe. But beware of characters who can easely do stun, like Ara. But don't rely on this skill so much for catch, this skill is feed a lot MP to your opponent and charge their awakening gauge. If used of ledge, you can freely move while the slashs still appears, but you will lost the last upward slash. Never use it in mid-combo.
This passive gives buff which increase your damage when your HP is below 50%. It means you must lost half of your HP for the buff to actives, skip it.
It gives extra reduction damage with same value as Reversal Fighter. The main different is this skill is always active, don't need to lost your HP. And also, if you lack of defense, Trained Body is helpful.
You can't continue your combo after it. And also, Flying Impact's damage isn't high compared to other special actives. Not worth to take for PvP.
Giga Drive - Limiter & Seismic Tremor
For Giga Drive, original (Limiter) is better. It gives buff which increase your damage and limit your active skill cooldowns to 1. The buff duration is longer than cooldown actually, if you notice it. I recommended to use it in awakening, the ghost core will prevent your opponent to escape, and nasod core's damage is increased also. Seismic Tremor's total damage is high, but it needs to clear huge area in front of you. It's hard to get full hits and usually your opponent manabreak at first few hits. Considering them, this skill can be waste of 200 MP.
If you take One Flash, this skill is a good combination of it. It has long-range, super armor frame, and higher piercing speed than Shadow Piercing. This skill will make BM so reliable in team matches. So, combination of One Flash and Shadow Thrust is good for team matches. It has lower SP investment than Emergency Escape! Because I take Sonic Slash, skip it.
With Lv80 cap, this skill is really good with higher chance. This passive is good combination with Shadow Piercing, Burning Rush, and Sonic Slash too maybe. Well.. It's goes againts my point of view about not depending on luck (please check Diabolic Esper skill build v.2), but take a look to skills I take, I know that Shadow Thrust willn't going to be good. If you getting combo'ed from behind while you face wall, it's just asks a reversal. Burning Rush for front defense, this passive for back defense. When you use Sonic Slash, your opponent willn't attack in front of you, and end up atacks you from behind. Just like asks this passive to active.
Hyper Active is user preference.
Video testplay for Type A: