A couple thoughts… It might be worth fiddling around with the poem in its entirety and seeing if you could even out the meter. Everyone’s technic is different but when I write I generally ad lib it the first time through. Then I go through, count the syllables, see what meter predominates, and play around with it to see if I can adjust the out of kilter lines to the selected meter. If I can’t do it without sacrificing some particularly valued line, then I select a different meter and try again.
“Who left Heaven’s throne, on Himself took alone,
The weight of the world in His hands?”
This bit seems like it could use some of clarification. The concept of taking the weight of the world on himself, and then holding it in his hands are similar, but the juxtaposition of the two lines putting it in different ways strikes my ear as just a tad odd somehow.