Extremely powerful. Darth Maul has to be one of the most underrated fictional characters ever. Some people think he was only an assassin. Nothing more. That couldn't be further from the truth. He was implied to be holding off Sidious while Talzin regained her power.

He landed a kick on Sidious, while rage amped from Savage’s death.

Fought against both Aayla Secura, and Mace Windu. Two of the strongest Jedi of their time.

Easily beat an angry Kenobi. Although the Jedi was weakend.

Charged Grievous, making him submit.

Without effort, defeated Savage. Someone who used his physical power to beat Anakin and Obi-Wan.

He ranks above Dooku in dueling.

Ventress was getting overwhelmed by Maul's strikes.

He's fast enough to dodge a rocket.

Create four afterimages while blocking blaster fire.

Spin his saber fast enough to block rocks being thrown by the force.

Jumped over an attack from Sidious.

And casually block an attack from a Jedi Knight. Without even looking.

He took Palpatine’s lightning for who knows how long.

Took a grenade from point blank range.

Maul didn't talk, even after Dooku used force lightning to try and make him.

Threw Kenobi all the way down a tunnel. Collapsing it.

Pushed away several battle droids.

Force pushed Grievous through a concrete wall.

He even destroyed a Star Destroyer's hyperdrive.

There you have it, Darth Maul is extremely powerful, and extremely underrated.