Aepele Fealcans are stupidly easy to get if you have good blunt cavalry. Then they self-perpetuate because they train into really good blunt cavalry.
Peasant rebels in Falcon territory are often groups of up to 20+ Aepele Fealcans. If you're in the area, spend time to chase them down, corner them, and then beat them up. You don't take a reputation hit to the Falcons for attacking the peasant rebels; you will, however, take a hit to bandit relations. If you have any decent relationship with the Falcons, and decent charisma (not sure how necessary this is), you can recruit them from your prisoner pool.
In my last play through doing just as described above, I recruited several hundred Aepele Fealcans and trained them up to Light Renweards and Renweards. At one point, I had too many Falcon blunt cavalry, and then devoted training to make my Aepele Fealcans into Sceotend Fealcans and Frod Sceotend Fealcans. After which, I stopped using Hired Mercenary units.
In short, just because you cannot recruit them from villages in large numbers, doesn't mean you can't get them in large numbers. Falcon vassalage is helpful but not required.
YMMV