As the Punisher he has no superhuman powers.
While he was Franken-Castle, Castle had superhuman strength to an unknown degree.
Castle once had a bloodstone fragment which had enhanced him in currently unknown ways, it had also given him some degree of a healing factor which has allowed him to recover from serious injuries including restoring him to his old self.
Master Martial Artist: Castle is a seasoned combat veteran of exceptional skills. He is well-versed in the arts of warfare and hand-to-hand combat. His styles of choice being Nash Ryu Ju Jitsu, (the four-style martial art founded by his Sensei Adam Nash and the Marine Corps LINE combat system) Ninjutsu, Shorin-Ryu, Hwarangdo, and Chin Na. He is an exceptional knife fighter who carries up to 3 or 4 different types of edged weapons, preferring the knife he learned to fight with in the USMC: the Ka-bar.
Expert Marksman: He is an exceptional marksman who is sometimes depicted as being ambidextrous in this respect. He is skilled in sharpshooting and knife throwing
Expert Pilot: Castle received airborne training with the U.S. Army and U.S. Navy Special Forces.
Demolitions Expert: He also received a U.S. Navy SEAL, UDT (Underwater Demolition Team), LRRP (Long Range Recon Patrol) training.
Expert Tactician: Armed solely with conventional weapons and motivated by a fanatical hatred for criminals like those who murdered his family, the Punisher has single-handedly incapacitated up to a dozen well-armed and experienced opponents in a single encounter and escaped uninjured. It is his military training and his attention to detail that allows him to achieve this.
The Punisher possesses the normal human strength of a 6'1" 200-pound man, who engages in intensive and extensive physical exercise. Frank is capable of press lifting up to twice his bodyweight and can press lift 400 lbs. Frank engages in a brutal regimen of calisthenics, katas and firing range practice daily, maintaining his combat skills and he does not drink alcohol or do drugs.
Castle once Relied on a "synaptic glue" medication to keep his mind together due to brain damage caused by his fight with Daken and becoming frankencastle.
Non-Superhuman Physical Conditioning: Castle is as susceptible to physical injury and disease as any other normal human, often having to rely more on strategy than strength when up against a superhuman opponent.
Military equipment as appropriate
The Punisher's first outfit was a form-fitting black Kevlar bodysuit with a large white skull on his chest. According to Frank Castle, this drew the attention and the aim of the criminals to his heavily armored body, instead of his more vulnerable head. Each tooth of the skull was actually spare ammunition for firearms.
Punisher chose not to utilize any costume outside of a black shirt with a white skull splashed across the front. His other clothing, which sometimes included combat boots, blazers, leather jackets, trench coats, bulletproof vests, body armor, black battle dress uniforms, and camouflage outfits was worn for the sake of protection or camouflage in urban and wilderness areas.
The Punisher employs a vast array of conventional firearms including machine guns, rifles, shotguns, handguns, knives, explosives and other weapons culled from common and organized criminals and military sources during his operations. A vast majority of his weapons have roots in military forces around the world, and typically employs weapons and accessories limited to military operations.
The Punisher often customizes his weapons for greater effectiveness with both standard and custom items including magnified optics, reflex sights, night vision scopes, flashlights, grenade launchers, sound and flash suppressors, bipods, high-capacity magazines and drums and various ammunition including hollow point or armor piercing bullets.