1. Judgement Cut – Shoots energy waves at you. To avoid, run/jump away. As always, it’s easiest to counter Vante when he does this. Get near him while evading the waves, then Stinger and continue spewing combos.
    
2. Round Trip – Vante throws his sword at you like a boomerang, sometimes circling you for a bit before returning to him. Keep shooting Summoned Swords to deflect the sword.
    
3. Helm Breaker (+ Stinger) – He’ll appear right above you and perform a Helm Breaker. Jump away from Helm Breaker, then perform Air Trick to avoid the upcoming Stinger. Air Trick will teleport and land you behind Vante, then attack.
    
4. Rapid Slash – Vergil charges forward quickly, leaving a trail of slashes behind him. Jump out of the way, it's safer than rolling. Attack as he's recovering.
    
5. Parry + Upper Slash/Rapid Slash – Vante parries you every so often and may counter with a 2-hit Yamato combo or Rapid Slash. Once parried, perform Air Trick/Trick Down to avoid his counter attack, but be careful if he does Rapid Slash. You may need to jump away again right after to avoid it. To avoid getting parried, don't hit him after he grunts. However, shooting will work just fine.
    
6. Final Judgement Cut – Vante does this move only after you take away about 60% of his life. He will DT and disappear before orbs appear everywhere. Run/jump away from those, and stay close to where you last saw Vante. Once done, Vante will reappear and be vulnerable for a bit, so attack!
    
7. Stinger – Vante does this move by itself only in the harder modes. When close to him, always be on the alert to jump in case he randomly does it. Although, if you do get hit, it takes time for Vante to put his sword away and Dante usually gets up faster than Vante can recover, so hit him while you can.

Pattern:

1. Vante often starts the battle with Judgement Cut so counter him. Other times, he teleports behind you and tries to slash you a couple times before he teleports and performs Helm Breaker. Avoid and counter by using strategy #3 above.
    
2. After a while, Vante will DT . At this time, DT Vante will still perform the same moves as he does in human form, so keep countering Vante to return him back to human form quickly. Use all of the strategies above with only once difference - quickly jump away after hitting him once.
    
   Reminder: For those who are inconfident in countering DT Vante, remember to activate DT to reduce damage.
    
3. After taking away about 50~60% of his life Vante will go into super DT state (where he says "You're going down!"). Vante is highly aggressive in this state so don’t bother countering/attacking him. Concentrate on EVADING.
    
   In this state, Vante will perform Helm Breaker continuously for about 6~13 times depending on how many times you avoid it. Jump/run away from all of them. The more times you get hit, the less number of times he does it, but you don't wanna get hit now do you. =P In between some of his Helm Breakers, he also does a 2 hit Yamato slash + Helm Breaker + Stinger, so use strategy #3 above.
    
4. Once super DT runs out, he will turn back into human and be vulnerable for about 3 seconds, so attack! After this, the pattern repeats itself.

Hard mode - Full video demonstration (3.32 MB)

1. Vante now performs Spiral Swords. Shoot as much as you can to break the Spiral Swords barrier fast to save time. He tends to perform Judgement Cut right after he summons Spiral Swords, so shoot as you dodge them. Such is a wonder of Vergil's capabilities. =P
     
2. Vante also does Spiral Swords when in super DT. This is probably the toughest part of the entire battle. Vergil tends to teleport right towards you immediately after he summons the swords, and his attack range becomes really wide with the sword barrier around him. To avoid, you have to jump away at the right time. It's a lot easier said than done, but the more you play against him the more you'll get used to it. In the worst scenario, activate DT to reduce damage.
    
   Another way, which is tricky, is to cancel out all his swords with Sword Storm before Vante disappears to perform Helm Breaker. To do this, the moment Vante pauses to summon Spiral Swords, quickly summon your own Spiral Swords as well. Do a Sword Storm a little before Vante's purple shield disappears. The objective here is to have your Sword Storm break all Vante's Spiral Swords right after his purple shield disappears. If your swords hit the shield or if Vante disappears before your swords actually hit his, this will fail. If you suceed, you won't have to deal with Helm Breaker + Spiral Swords, which makes it SO MUCH EASIER.
    
3. In any case, keep running and jumping away to avoid his consecutive Helm Breakers. If you see him pause for a bit after Helm Breaker, it means he's going to do a Yamato 2 hit slash next. To avoid getting hit, RUN away from him as soon as you notice the pause. Any slower and you won't be far enough to avoid the wide ranged slash. Once dodged, continue to use strategy #3 as written in Normal mode.
    
4. Using DTE wisely throughout the battle will help you save a lot of time, and may even help you knock him out of DT if necessary. Like Dante, Beowulf is also the best devil arm for this battle. Spam Starfall rebounds for maximum damage in the shortest time.