Eventually, Belial still did not choose to seal the dark energy here because, unlike Absolut Particles, this dark energy cannot be directly absorbed by their bodies.
Once this energy is used, the Light Power inside their bodies becomes unusable.
This actually weakens them.
It's not worth the loss.
This is the difference between the Ultramen of the Land of Light and the Ultramen of the Tiga worldview; they are more like biological beings, with their bodies going through changes in appearance akin to humans, transitioning from infancy, childhood, adolescence, adulthood, middle age, to old age.
In the Tiga worldview, however, whether it be Tiga or Dyna, they essentially are Light and the strength of their transformation directly correlates to the physical condition of their human form. Yet, they do not age as their human form does.
This difference among the giants from the two worlds is why Belial and Toregia had to give up the dark energy here.
