Egres said:?
That passage allows a monk to benefit from spells, psionic powers, spell-like abilities and supernatural effects that enhance or improve Manufactured or Natural Weapons.
This doesn't have anything to do with prerequisites.
How else do you benefit from a feat's effects, except by meeting its prerequisites?
Accept it.
Which part of "A monk's unarmed strike is treated both as a manufactured weapon and a natural weapon for the purpose of spells and effects that enhance or improve either manufactured weapons or natural weapons" did you fail to understand?