Again the main culpit is that most polearms got popularity after the classical era. Most D&D "named generic" weapons are based on ones from mythology and polearms weren't much used then.
The Ancient Greeks, Romans, Celts, Egyptians, Nubians, Sumerians, Chinese, etc didn't use polearms besides spears much.
If you convert the Greek hero and God weapons to generic forms, you'll get a bunch of spears, javelins, pikes, and tridents.
Best best is to convert Three Kingdoms China weapons. They used a few polearms.
A DM gave me a Halberd of Nonpursuing once.