Kamala Harris would be the first woman to serve as commander in chief while Trump would be the second president in history to win a non-consecutive term.
Oh yes, the second time things happen is truly something described as "historic". Instead of twisting themselves in knots to find a non-disparaging "historic" feature, just use the obvious and more serious one. First woman vs. first convicted felon.
Or even “vs only president to be impeached twice,” “only president to be elected after losing and being impeached” “first president elected by an electorate that knows full well he is a rapist,” etc.