That was the first time Bu Yeon and Nak Su were both active at the same time. Bu Yeon used Nak Su's ability to absorb energy while at the same time she also used her own powers to make the transfer pure.
Notice the difference in special effects.
1: A shifter absorbing another person's energy, the sfx is dark energy or shadow. 2: Bu Yeon purifying the energy being absorbed by Nak Su (as a shifter) is light, intense light.
I think Jang Uk also saw it and this is the reason why he embraced her. He understood the difference. He understood the meaning of the intense light.
Secondly, remember during the mirror episode? What broke it was Bu Yeon's power, the intense light (or energy).
Third, in the preview, Mu Deok's temporarily blind again. The effect of the intense light did not show up immediately (like in the mirror episode) because she just absorbed an energy. As Nak Su, her own power is much stronger than Bu Yeon at that moment. But once that energy she absorbed "calmed down" (for lack of a better term), Bu Yeon, having activated herself, overpowered Nak Su thus Mu Deok (the body) turned blind temporarily again.
Once Bu Yeon's power "calms down" Nak Su and her will be on equal footing again, cancelling each other … which would mean since Nak Su is the one with control over the body, Mu Deok will get her sight back again.
While it is understandable what happened to the guilty parties, I think they still should've shown it, especially the three idiots. Seeing the three idiots sentenced gives a greater impact to the ending, then they can pan back to Soo Jae and show the ending that they've shown.
But overall, I like the message: the laws has flaws, good lawyers won't use it to cover up sins.
1 
Notice the difference in special effects.
1: A shifter absorbing another person's energy, the sfx is dark energy or shadow.
2: Bu Yeon purifying the energy being absorbed by Nak Su (as a shifter) is light, intense light.
I think Jang Uk also saw it and this is the reason why he embraced her. He understood the difference. He understood the meaning of the intense light.
Secondly, remember during the mirror episode? What broke it was Bu Yeon's power, the intense light (or energy).
Third, in the preview, Mu Deok's temporarily blind again. The effect of the intense light did not show up immediately (like in the mirror episode) because she just absorbed an energy. As Nak Su, her own power is much stronger than Bu Yeon at that moment. But once that energy she absorbed "calmed down" (for lack of a better term), Bu Yeon, having activated herself, overpowered Nak Su thus Mu Deok (the body) turned blind temporarily again.
Once Bu Yeon's power "calms down" Nak Su and her will be on equal footing again, cancelling each other … which would mean since Nak Su is the one with control over the body, Mu Deok will get her sight back again.
Weirdest ad I've seen from Korea. hahahah
I can't wait for episode 6, I wonder why Yu Jin cried.
Rollercoaster ride now …
Hahahaha
2. Fire = ???
3. Wind = ???
4. Earth = ???
The question is, are they following æther (Western/Japanese) or metal (Chinese/Korean) elements?
5. Æther (Western and Japanese fifth element) = Bu Yeon = energy
5. Metal (Chinese, Korean fifth element) = ???
All five elements together = Light = pure energy = power from the heavens = Ice Stone.
The anti-thesis of Light is Shadow, thus the anti-thesis of all 5 elements:
- Shadow = Jin Moo (shadow = copycat; fake; sinister; evil; selfish)
While it is understandable what happened to the guilty parties, I think they still should've shown it, especially the three idiots. Seeing the three idiots sentenced gives a greater impact to the ending, then they can pan back to Soo Jae and show the ending that they've shown.
But overall, I like the message: the laws has flaws, good lawyers won't use it to cover up sins.
They may have wasted an entire episode for a flashback that could've been placed in other episodes but they redeemed themselves in the ending.
Well done.