Black Panther without the herbs and enhancements would still be very badass.
Baron Zemo--The jury's out on whether or not this guy is currently a hero or villian, but last time he appeared with the Thunderbolts he had very noble intentions, just somewhat wonky means to his end. He has access to advanced tech, and can create it, but he usually doesn't use it, being to proud to rely on technology when he's obviously a superior Aryan. And it's nothing more than what Batman has. Usually he carries a broad sword and guns. Also a Lueger or Walther, more sentimental than anything but he has had occasion to bust it out. Same with his dad.
Citizen V--Various Citizen V's have operated since WWII, all doing so without physical enhancements. Sometimes they have access to advanced tech that puts them out of this category though.
Swordsman--both I and II were very good fighters, especially with bladed weapons. Have to wait for more info on the new one (appearing in Thunderbolts! Check it out!)
Sans Redwing and flight harness, the Falcon is also a very good regular guy. A few issues of Priest's Cap and Falcon had him flightless as his harness had been destroyed (and Redwing's cool, but it's not like he adds that much) and he still kicked ass.
Most of the Union Jack's have operated, successfully, without powers at one point or another.
Just recently, seen in She-Hulk, The Challenger was somehow brought forth from WWII to present day. "Bill Waring is a meek and harmless law student who is a victim of bullies. He never does much about this, but when his father is killed for giving evidence to the D.A. about an alliance between the Mob and a prominent local politician, Bill swears vengeance. He travels around the world, learning the proper skills to avenge his father and kill criminals. (Capturing the bad guys is not a high priority for the Challenger, who is very much in the Killer Vigilante mode.) The Challenger learns jiu-jitsu in Japan. He learns chemistry in Tibet (Tibet???). He learns nerve control in India, so that he is immune to pain. He learns swordsmanship in Paris and marksmanship in Germany. He learns how to fly in England. He learns how to box. He learns every imaginable skill which might help him in the war against crime. And then he returns to America and avenges his father, after which he takes on various other criminals. " From http://www.geocities.com/ratmmjess/gaguide.html
Nighthawk--originally created as a Batman ripoff for the Squadron Supreme and Sinister. Very cool, our reality's Nighthawk later gained powers, broke from the Squadron Sinister and redeemed himself in the Defenders. The one in the Squadron Supreme's reality never gained powers but remained an influential hero.
As for a few villians, even though the thread doesn't ask for them, I find it's always good to give both sides of the coin.
Boomerang is just a normal guy, he used to have boot jets I think, but last time I saw him, he'd ditched those.
Batroc, the master of Savate. Goofy, for sure, but he has put up a few good fights.
Crossbones--no powers but usually gave Cap a run for his money.
Zaran--the weapon's master. Very good fighter, expert usage of pretty much any weapon.