(a) Notwithstanding the breadth of discretion granted to a trustee in the terms of the trust instrument, including the use of such terms as "absolute," "sole" or "uncontrolled," the trustee shall exercise a discretionary power in good faith and in accordance with the general and specific terms and purposes of the trust and the interests of the beneficiaries.
(b) Subject to subsection (d) of this section, and unless the terms of the trust instrument expressly indicate that a rule in this subsection does not apply:
(1) A person other than a grantor who is a beneficiary and trustee of a trust that confers on the trustee a power to make discretionary distributions to or for the trustee's personal benefit may exercise the power only in accordance with an ascertainable standard; and