Finishing
Gran is using a extremely straightforward method to merge two elements. And all that needs is an extreme control of energy. When Sam saw this, he felt like his level of control might even be less than her own.
It is that critical and delicate.
But it is simple to explain. Unlike Sam who channels both energies at the same time by taking advantage of his beast like meridians, Gran channels one energy after another. She channels, shadow energy and space energy one after another in extreme speeds that there would be an overlap between both energies which gave her the opening to use both energies combined.
If one has a great command and control over their own energy with a perfect timing, they can merge any two energies.
Gran smiled at Sam as she reached a proper state to move, but just as she was about to make that move, Sam also returned her smile and used his own version of shadow and space elemental merge.