Darth Maul is also a quite interesting fighter as he focuses primarily on lightsaber technique over force abilities and dun moch...The primary component of Darth Maul's lightsaber technique is Juyo, which is what provides Maul with his offensive technique as a duelist. Juyo is known for its unpredictability, which plays off of the unfamiliar nature of Maul's double bladed lightsaber quite nicely. Juyo is also known for it's fast paced and aggressive offensive, which also plays well off of Maul's double bladed lightsaber given that he can strike with two blades more frequently than he could with one. Maul however was not dependent on his double bladed lightsaber and could still function with a single blade. When applying Juyo with a single bladed lightsaber Maul compensated for his double bladed lightsaber's greater striking speed and his opponents' unfamiliarity with it, with the greater maneuverability provided by a single bladed lightsaber.
Maul supplements his offensive dueling capabilities with the aggressive martial art known as Teras Kasi. Teras Kasi is perhaps the most effective martial art for a Sith to compliment their dueling skills with considering that it was developed and geared for fighting Jedi, exactly the kind of opponent a Sith Lord like Maul would face in a lightsaber duel. Maul's mastery of Teras Kasi is to the extent that his master considers his body as lethal as his lightsaber blade, and it is very prevalent in his fighting style. Given how busy Maul's hands are in combat he more frequently utilizes kicks in combat to the extent where he's thrown at least 6-7 kicks in half of his on-screen fights, once to the extent where it was actually lethal to a Jedi, and another time actually managing to land a blow on Sidious. Maul's intense and brutal physical training at the hands of Sidious was instrumental in specializing his body for such attacks, though after losing his legs, the new cybernetic legs he receives makes his frequent habit of throwing kicks in a lightsaber duel all the more effective.
With Maul's mastery of Juyo and Teras Kasi he is a very offensive fighter, and as such he'd be considerably less comfortable on the defensive. Nevertheless Maul does maintain a capable defense in his dueling repertoire. It is likely that much of Maul's defensive technique is derived from his skill in Niman. Niman's balanced jack-of-all-trades nature provides Maul with no weaknesses for his opponents to exploit against him. Niman as a jack-of-all-trades style also provided Maul with some insight into the other forms, allowing him to more capably respond to them in combat. His defensive technique was also well served by his double bladed lightsaber, given the defensive coverage provided by two blades. Unlike his offensive technique, I do not believe he ever truly compensated for the loss of his double bladed weapon in this regard. Given how undeveloped his defensive technique was in comparison to his offensive technique, Maul would also utilize aggressive moves and maneuvers derived from Juyo and Teras Kasi in his defensive technique to keep his opponents at a safe distance while also keeping his opponents from closing in by creating distance with the acrobatics of Teras Kasi. As such Maul's defensive technique is mainly comprised of not presenting a weakness, while maintaining a reasonable distance with aggressive techniques and acrobatics.
Then we get to Maul's mastery of Jar'kai which impacts his fighting style in a few different ways, pretty much all of which are related to armament. First of all, he likely got to Jar'kai through the stepping stone of Niman, which he then used to attain mastery of the double bladed lightsaber. The second and more obvious impact is his skill in dual wielding. When wielding two lightsabers, he further increases his effectiveness with Juyo, as it provides him with the striking speed of two blades without the movement hindrance of the double bladed lightsaber, also increasing his options in combat, and thus his unpredictability as well.
Darth Maul was essentially Sidious's weapon and his skillset reflects that. He is specialized for offense, maintaining combat expertise in several weapons through Jar'kai, a fast paced offensive through Juyo, knowledge of other forms through Niman, skill in hand to hand combat through Teras Kasi, and a defense that utilized minimization of weakness and aggressive techniques to keep his opponents at a distance to compensate for his relative lack of defensive techniques. Maul was brutal and aggressive, but as a result of his vast array of techniques he was also versatile and thus unpredictable, a two edged sword if you will (full pun intended). For these reasons I judge Darth Maul's fighting style to be unique, resourceful, and effective.