Click to expand.
Ambidexterity: While not born so, Leonardo is trained so. Having dual wielded weapons all his life, Splinter further reinforced this by having his students eat with the 'wrong hand', do other things with the 'wrong hand' and otherwise make sure they could use both hands equally for anything. He can even throw kunai and shuriken with either hand, as the situation calls for.
Blacksmithing: From the first time Leonardo broke his ninjaken, Master Splinter trained him in the art of Blacksmithing. Leonardo was told he needed to rely on himself and forge his own ninjaken, rather than buying things from human smiths or on Ebay or whatever. As a result of the constant damage to his weapons, Leonardo has had to forge multiple ninjaken for himself, and due to their breakage, he's already forged his 11th set. This includes his 'spare sets' that he keeps handy in case his primary set breaks, again. Leonardo gets better every time he must forge new ones, and more recent models are sturdier than his first tries.
Chi Gong: A special ninja art that controls breathing and heart rate. Should Leonardo take a wound that would be very difficult to heal from...this will not heal the wound, but it'll let him triple how long he can survive with that wound till he can be treated for it. This also helps in extreme environmental conditions, such as the icy cold of the arctic or the heat of the Sahara desert.
Cross Training: For purposes of deception, mostly, Leonardo has been trained in the weapons of his brothers...the bo staff, sai, and nunchuku. He is not a master of those weapons, however, merely competent enough to fake it until the turtles switch back to their real weapons, having completed their deception.
Environmental Useage: It is not enough to simply master one's self and one's weapons. One must master the world around them. Leonardo takes advantage of whatever is around him to gain an advantage over his enemy, and always kills the lights if it is possible to do so, so he can operate in the dark. The shadow is his friend. He is especially dangerous in the sewers, since that is his home, and an opponent would have a near impossible time trying to find him down there.
Iaijutsu: The quick draw technique of the samurai. Because Leonardo uses swords, he has perfected pulling this trick with his ninjaken, even though the weapon is stored behind his back. Such strikes are as quick as any Samurai would use from a sword at their hip.
Kenjutsu: This is the art of using a single sword in combat. When referring to a ninjaken, Leonardo has the benefit of mastery. Wielding a single sword grants precision and accuracy wielding two blades at once does not.
Leadership: Leonardo leads, as the old song goes. There is a reason for that...as the most serious of the turtles, he is most likely to keep his head in rough situations. More importantly, he also understands the strengths and weakness of his brothers, knowing to send Raphael in to situations where strength is required, Mikey into speed situations, Donnie into fight at range at situations. He also has studied tactics, and Sun Tzu's the art of war is his favorite book for a reason. Having read through that book dozens of times, he's learned a few things. Strategy, which is different from tactics, is another thing he studies to make sure the plan going in is solid. Tactics is adjusting on the fly, and he does plenty of both.
Ni Ten Ichi Ryu: A fancy way of saying 'training with two ninjaken', this is Leonardo's primary form of combat. With ninjaken in each hand, he specializes in swift, deadly strikes. He must also take slightly more care than his brothers when he fights, as the ninjaken is the only weapon on the team truly designed to be lethal in combat. Anything can be a lethal weapon in the hands of a ninja, but swords are sharp and cut. As a result of long training, Leonardo can even use his ninjaken to cut through metal, such as robots or trash cans or other such things. He has spent more time training on this then any other form of combat he knows, and his enhanced skill with his primary weapons is notable.
Ninja Tools: Leonardo has also been trained at using other Ninja tools, such as throwing kunai and shuriken, using a dagger-like tanto, climbing claws, grappling hooks, smoke bombs. He's even spent time learning the yumi bow and archery. Leonardo's extra focus on training has helped him use these things at a high level. It also helps he's been training like this for years with such things.
Pop Culture: Time spent living in the abandoned subway tunnel the turtles call home with Master Splinter can lead to boredom fast, but during free time they have outside their training, they have found ways to keep themselves occupied. Television, newspapers, video games, magazines, books, even Netflix, one of the greatest gifts to turtle-kind. You name it, and Leonardo has immersed himself in it. This has left him knowledgeable in a lot of worthless stuff, but it sure comes in handy when looking for just the right thing to say. He is also a fan of video games, new age music, and the TV show Space Heroes, which is loosely based on many of the more famous space oriented heroes of the world.
Stealth: The trademark of the Ninja. Do not be seen, ever. Do not be heard, ever. This is not merely training to not be seen and not be heard, it is understanding the psychology of how people look around for somebody they're trying to find, and using that to not be found. It is knowing things like people rarely look up. It is masquerading as inanimate objects. It is disguising one's self (insofar as it's possible for a mutant turtle) to not be picked out of a crowd. It is also things like being trained to walk on rice paper from Splinter from a very young age, and Splinter not being satisfied till he can't hear a thing.
Trilingual: Leonardo speaks English and Japanese, and is perfectly fluent at both. He usually uses Japanese in combat, as few Americans speak it. Were the turtles in Japan, however, they'd use English. The idea is to be speaking a language your enemy does not. As a result of being in South America for a while, he's started to pick up pieces of Spanish. It's no more than what you'd learn after a high school Spanish class though.
Unarmed Combat: Leonardo has also been trained in the unarmed combat of ninjutsu, using misdirection, along with feet and hands to deal swift, powerful strikes designed to put an enemy down before they can call for help and reveal his presence. Because they are turtles, Leonardo has also learned how to blend his shell, particularly the reinforced back part of his shell into his combat style, using it as simply just another weapon, due it being a very hard surface.
Leonardo
