(a) The insurer may in any life insurance policy or annuity or pure endowment contract limit its liability to a determinable amount not less than the full reserve of the policy and of dividend additions thereto in event only of death occurring—
(1) as a result of war, or any act of war, declared or undeclared, or of service in the military, naval or air forces or in civilian forces auxiliary thereto, or from any cause while a member of any such military, naval or air forces of any country at war, declared or undeclared;
(2) as a result of suicide of the insured, whether sane or insane, within two years from date of issue of the policy; or
(3) as a result of aviation under conditions specified in the policy.
(b) An insurer may specify conditions pertaining to the items of subsection (a) of this section which in the Commissioner's opinion are more favorable to the policyholder.