Skills: The mc does gain a lot of skills along the way as he levels up with his servants, the skills being.
Rewrite: The ability for the mc to Rewrite any part of his body, either making it stronger, faster, or more durable.
Creation: The ability for the Mc to create whatever equipment or weapon he has come in contact with.
Avenger: The mc gains the ability to use his servant's skill for a limited amount of time.
Override: A skill that uses the Mc's deepest hatred and anger as a source of Mana turning him into a bloodthirsty killing machine.
Saber:
Encounter: With the help of her sword, she absorbs as many attacks as she can take, and once her blade has collected enough she pours all the attack into one hit against her opponent.
First heal: Helps heal her injuries and another magic paralysis, like mind control, Poison, etc.
Excalibur: Her Noble Phantasm is considered to be one of the strongest.
I'll release the rest soon.