No appointment made by will, in exercise of any power, is valid unless the will is executed in accordance with Article 5.

Paragraph (1) applies notwithstanding anything to the contrary in the instrument creating the power.

A will executed in accordance with Article 5 is, so far as respects the execution thereof, a valid execution of a power of appointment by will, notwithstanding that the instrument creating the power expressly requires that a will made in exercise of such power should be executed with some additional or other form of execution or formality.