*NOTE This list is based off of the Marvel Power Grid (which ranks Fighting Skill) and my personal opinion that I reached after researching the characters mentioned below. These characters will be taken from their comic book depictions and will exclude any other medium.
12. Silver Sable
Silver Sable is a mercenary and extraordinary hand-to-hand combatant in peak human condition. However her over reliance on weapons drags her down on a list where hand-to-hand fighting skills are the most important factor.
11. Moon Knight
Marc Spector is the schizophrenic vigilante Moon Knight. He is a heavyweight boxing champion with training in Kung Fu, Savate, and Judo. Skilled enough to defeat Punisher and Deadpool in combat
10. Black Widow
Black Widow is the codename of Natalia Romanova, an Ex-Soviet Spy enhanced by a second rate version of the Super-Soldier Serum (which enhances strength, speed, agility, reflexes, durability, and senses). She has defected to SHIELD and is an expert in Sombo (Russian Martial Art), Boxing, Karate, Judo, Aikido, Ninjutsu, Savate, Muay Thai, and many forms of Kung Fu. Her mastery in acrobatics allows her to perfom a vast array of agility-based feats. Natalia is also a Master Seductress, this skill has proven to be useful on multiple occassions.
9. Elektra
Elektra Natchios holds the reputation of being one of the most skilled assassins in all of Marvel. Elektra was born into a very rich and important family, the assassination of her father left her seeking revenge. She trained under Stick like Daredevil. However, she has mastered Ninjutsu, Aikido, Kendo, Karate and is proficient in most martial arts originating in China, Thailand, and Japan. Elektra has also trained with the ancient mystical ninja clan known as The Hand. She's in peak human condition and has mastered many weapons.
8. Daredevil
Although he is blind, Daredevil's remaing senses compensate for it, by functioning at superhuman levels. He has trained under Stick (a martial arts grandmaster) and has conditioned his body to the point of peak human. Daredevil is a Master Acrobat whose equilibrium is on par with Spider-Man's, and he can easily dodge bullets. Daredevil's fighting style is a combination of martial arts that he is skilled in (Not quite mastered in all of these forms.) Boxing (Mastered), Ninjutsu (Mastered), Jujutsu, Aiki-jutsu, Savate, Krav Maga, Capoeria, *Escrima stick fighting (he has demonstrated proficiency with this weapon and can throw it with superb precision. He has mastered stick fighting), Aikido, Greco-Roman wrestling, Karate, and Kung fu. Daredevil has separately fought Captain America, Wolverine, and Black Panther to a stand still.
7. Stick
Stick trained both Elektra and Daredevil, two of the most accomplished martial artists on the planet. This blind old man has sparred both of his disciples and they couldn't even manage to get the upperhand in that fight. That in itself is a huge feat. Stick is a grand master in most martial arts that originate from all of Asia! Stick has had well over half a century of martial arts training and ample experience in using it.
6. Captain America
Physically and mentally enhanced by the Super-Soldier Serum, Captain America is by far one of the Top Martial Artists on the planet debatably even higher. He fought in WW II, where he learned hand-to hand combat skills and weapons proficiency. He has mastered many martial arts in his lifetime, but his fighting style mainly consists of Boxing, Judo, Jujitsu, Karate, and acrobatics ( his acrobatics are either on the level of Daredevil or most likely higher).
5. Black Panther
Ingesting the magical Heart-shaped herb T'Challa's physical abillities were acclerated to (lowl-level) superhuman. T'Challa earned the right of Black Panther through rigorous combat training that started at birth! T'Challa is an expert in almost all forms of unarmed and armed combat. He is a master in all martial arts including the secret ones native to Wakanda. He utilizes acrobatics in combat and is on the level of if not better than Captain America or Daredevil as a gymnast/acrobat . Though he has beaten Captain America and has overpowered Wolverine twice while Wolverine was using his adamantium claws.
4. Wolverine
Wolverine is the only mutant on this list. His physiology is enhanced beyond human capability, this coupled with his adamantium skeleton and claws make him superhuman. Wolverine has been alive for at least a century most likely more. In that time he has mastered every form of fighting style on the planet. Wolverine has beaten and even trained some of the best combatants in the Marvel Universe. Wolverine has fought in the American Civil War, World War I, World War II, and the Vietnam War.
3. Taskmaster
Tony Masters (Taskmaster) is a master of all fighting styles on the planet. This is due to his "photographic reflexes". This allows him to perfectly imitate any physical action he has ever seen in his life. For example he has mastered the various fighting styles of Ant-Man, Batroc, Beast, Black Widow, Boomerang, Bullseye, Bushwaker, Backlash, Black Knight, Black Panther, Captain America, Genis-Vell, Cable, Crossbones, Daredevil, Deadpool, Elektra, Falcon, Fatale, Firestar, Hawkeye, Iron Fist, Justice, Libra, Machete, Moon Knight, Oddball, Power Man (Luke Cage), Puma, Punisher, Razorfist, Shockwave, Silverclaw, Silver Samuri, Spider-Man, Shatterstar, Swordsman, Tigra, Tumbler, US Agent, Warbird, Wolverine, and Zarran. However he might be able to use their fighting styles, but he can't perform them to the same degree if the individual he is mimicking surpasses him physically. An example being he could throw a shield exactly like Captain America, but since Cap is way stronger than him the amount of power behind the throw will be significantly less if Taskmaster attempted to throw it. Tony is an Olympic-Level athlete and has trained super-villains, henchmen, agents, and superheroes in the art of combat.
2. Shang Chi
Shang-Chi is so skilled in hand-to-hand combat that it might as well be considered as a superpower in itself. Like Iron Fist he can use chi energy. He has defeated a multitude of highly skilled and superhuman opponents at a single time with ease. He is a grandmaster in all forms of Chinese martial arts with training that started at birth. Shang has mastery of his nervous system meaning he can deaden his body to physical pain, and even slow down his bleeding rate. He is regarded as a better hand-to-hand combatant than Iron Fist, though Iron Fist is arguably more powerful.
1. Iron Fist
Iron Fist (Daniel Rand) is a master of K'un-Lun's martial arts and is proficient in many of Earth's, including but not limited to: Kunlunquan, Shaolinquan, Judo, Aikido, Ninjutsu, Karate, Boxing and street fighting. He has access to the knowledge, experience and skills of all the Iron Fists before him. He has held his own and even beaten many of the people on this list. Through harnessing his Chi Energy he can enhance his physical abilities to superhuman levels and project the chi energy. This makes him an extetremely powerful combatant and one not to be overlooked.
Sources Cited
"Comic Vine - Comic Reviews, Videos, Forums and Wiki." Comic Vine - Comic Reviews, Videos, Forums and Wiki. Web. 24 Mar. 2016.
"Marvel Database." - Wikia. Web. 24 Mar. 2016.