Tri-Klops's place in fiction pretty much varies on whomever is writing. In mini-comics and the original cartoon he was practically He-Man's equal (or an oaf), and in the 2002 series he was more of a mad scientist type. The classics version has him as a blind bounty hunter and his visor allows him to see. The visor is pretty much Tri-Klops trademark gimmick. Once again depending on the writer, it's either cybernetic or magical. Generally the visor gives him a variety of vision related special abilities. Seeing all around him, around corners, through things, great distances, optic blasts... you name it. Whatever the writer comes up to match the hunter/swordsman's abilities at the time.
Sometimes I wonder if Tri-Klops inspired Blade from the live action movie. They're pretty similar. Aside from the visor, the two aren't that different. Weirdly enough, in the Filmation series bible gave him a more interesting back story. Tri-Klops, Evil Lynn and Beastman were originally crew members on Queen Marlena's spaceship (she was an astronaut who crash landed on Eternia). They had mutated in the crash which somehow lead to them joining the Evil Warriors. This origin was abandoned. Probably because somebody realized the awkwardness of the Queen watching her son beat up former colleagues on a regular basis. "Go son, stomp a mud hole in his ass and walk it dry. He never paid me back for that Starbucks."