Slade is enhanced due to a military procedure making him almost superhuman.
Enhanced Mind: Able to utilize 9 times more than a human's full brain capacity for information processing and sorting, Deathstroke's mind is virtually a computer built for strategy and problem-solving, one that works at optimal ability even when under stress and fatigue. Using his superior problem-solving skills, Deathstroke can work out a battle ahead of time for many possibilities and predict enemy movements and tactics after the battle has engaged by recalling and utilizing memorized mannerisms acquired through past experience on a moment's notice. He is also ingenious in devising solutions against superior aspects of opponents, can observe and exploit, and can calculate distance, speed, and time at lightning speeds; his sense of timing is superb, bordering on perfection.
Enhanced Reflexes: Deathstroke possesses enhanced reflexes. The speed at which he reacts allows him to dodge fast-moving projectiles such as arrows and bullets. He can usually out-react even the fastest humans, no matter how well-trained.
Enhanced Strength: His entire muscular system was hardened and strengthened, allowing Deathstroke to be "as strong as 10 men".
Enhanced Stamina: Deathstroke can exert himself at peak capacity greater then any human could.
Enhanced Speed: Ability to run at speeds of up to 30mph and long distances far out-performing any Olympic athlete.
Enhanced Senses: Deathstroke's senses have been augmented to higher levels of ability. He can hear, see, and smell things better than a normal human.
Regenerative Healing Factor: With an enhanced ability to heal damaged tissue, the rate at which Deathstroke's body recovers from injury and capable of being repaired before death. As such, Deathstroke's body can take a tremendous amount of punishment before succumbing to death. Simple gunshot and stab wounds, cuts, and broken bones can heal faster then normal. He was once impaled clean through his chest, and it did nothing but slow him down and cause great pain.
Enhanced Immunity: Deathstroke's regenerative abilities have some affect on his body's ability to process through harmful, foreign substances and he has become naturally immune to deadly poisons and illnesses.
Retarded Aging: An important aspect to note is that while Deathstroke is apparently aging, he does so very slowly, appearing younger than he actually is. One revival actually caused a reversal of age, however, this has yet to be seen again and the affects were eventually reversed by another return from death.
Masterful Tactician: Slade is most likely the greatest strategist and tactician on the planet always calculating his opponents moves before hand he even single handedly defeated the entire JLA roster. He has been compared to Batman in terms of tactical methods. Even against metahumans he has proved more than a match for them all at once with time to prepare. Roy Harper once claimed the Slade was, "The worlds greatest tactician."
Skilled Martial Artist: Trained in hand-to-hand combat and when he was in the Army, he proved himself to be one of their best fighters. During this time, he received Martial Arts training through Boxing, Jujitsu and Karate. After mastering these Martial arts he furthered his studies when he sought an assassin known as Natas to train him in the ways of Ninja and had studied assassination techniques. After this he became the man known as the Deathstroke. His physical prowess is so great that he fought Batman to a near standstill and Batman only defeated him during the Infinite Crisis storyline when he had the help of Nightwing and Robin.
Enhanced. His strength was likened to having the 'strength of ten men'. Able to press lift at a minimum of 800 lbs.
Deathstroke's helmet and armor are lined with Kevlar and later promethium mesh, making it incredibly resistant to conventional injury. Amongst other things, Deathstroke has been shown to carry a specially designed multi-million dollar flash-bomb capable of incapacitating the entire Justice League, including Superman, although only long enough for him to make an escape.
A Promethium Sword