Say What?

The following are colloquialisms/idioms written in their literal form. Try to find all four.

Example: A Panthera Pardus is incapable of altering its texture. (A leopard can't change its spots)

1. Revert to the first quadrilateral of equal sides and angles.

2. One suffering from Macular Degeneration guiding one with less than 1/10 of normal vision.

3. Restrain your multiple Equus caballus.

4. The writing utensil containing small amounts of ink is more puissant than the iron hand-held weapon.