Before you add any new weapons, give some consideration to the conceptual and mechanical redundancy already in the weapon chart.
The problem with spears and tridents being mechanically identical isn't a problem of lack of differentiation... it's that spears and tridents are very very similar weapons. The game doesn't need both, and it doesn't need anybody to add a yari, assegai, or qiang.
That said, longswords and battleaxes work a lot differently in combat, and it would be nice if D&D represented that. I would recommend reading some HEMA literature for inspiration before adding any crunchy mechanics.
Finally, I would advise against making all weapons viable. Some weapons are crappy and should be mechanically represented as being crappy. Anybody fighting with a club, maul, or whip against a rapier-wielding opponent of equal skill, is at a disadvantage. That doesn't mean crap weapons shouldn't remain in the game; bandits and goblins gotta use something after all.
The problem with spears and tridents being mechanically identical isn't a problem of lack of differentiation... it's that spears and tridents are very very similar weapons. The game doesn't need both, and it doesn't need anybody to add a yari, assegai, or qiang.
That said, longswords and battleaxes work a lot differently in combat, and it would be nice if D&D represented that. I would recommend reading some HEMA literature for inspiration before adding any crunchy mechanics.
Finally, I would advise against making all weapons viable. Some weapons are crappy and should be mechanically represented as being crappy. Anybody fighting with a club, maul, or whip against a rapier-wielding opponent of equal skill, is at a disadvantage. That doesn't mean crap weapons shouldn't remain in the game; bandits and goblins gotta use something after all.