Weakness

All of the Assassins looked behind them but didn't find anyone when they turn their head towards the mother daughter duo they found a small kid standing between them and mother daughter duo. They were all shocked the Assassins saw a kid with silver hair and red eyes rotating standing infront of them. Shuri and Akeno were also shocked but they knew who that kid was.

Shuri: What are you doing here please runaway from here.

Assassins: Kid what do you think you are doing? Doesn't matter we will also kill you.

The kid turn towards Shuri and Akeno and put them under a simple genjutsu to make them leave the compound and go towards the forest where they will meet Rias. Seeing them leaving the Assassins tried to attack them but kid took out a sword from somewhere and blocked them. The swords which he was not able to block by his sword were deflected by VECTOR MANIPULATION. All the assassins were shocked and they were raging. Then there were several golden ripples in space and lot of weapons came out of them and pointed swords and lances towards all the assassins.

They were again shocked but the kid launched those weapons and soon all the Assassins were dead except the leader. His back was filled with cold sweat, he knew for sure that he will die today. Then he noticed the kid's eye rotating again and he lost the ability to move his body. The kid put him in a genjutsu. Ofcourse the kid was Sparda

Sparda: Who gave you the information about their location?? Who told you that they would be alone??

Leader: I don't know his name but he was a fallen angel with 10 wings.

Sparda: Thank you for the information now you can die.

He says that and swings his sword and cuts off his head. Then he took out a fire torch from GOB and light the house in fire. Then he wait for a bit and used his SPACE ability to escape towards some alley. He then directly fell to his knees and tried to catch his breath again. He took out a senzu bean from inventory and ate it.

Sparda: Even I have mastered the GOB and VM (Vector Manipulation. I will use VM from now on for this) my body cannot bear the toll.

Even he had mastered both GOB and VM his body was unable to bear the burden. He also had a huge amount of devil energy which was also adding the burden and using SHARINGAN to use genjutsu wasn't also helpful in this matter. He was still a 6 year old kid. His body was unable to bear the burden of using those powers and breaking from inside. He was healed instantly but he was still getting tired and even if physical injuries are being healed his mind was having the burden which can't be healed by instant regeneration.

After few minutes he was able calm his mind completely then he started walking towards the hotel to get some rest it was a really tiring day for him. As soon as he reached the hotel he went to take a bath.

Sparda:<Before mastering new powers I need by body to grow up I am currently unable to even use all my powers for this short time, I need a lot of work to do>

He then got out of his bath and went towards his bed and directly fell asleep he even forgot to collect his awards for the mission.