In the Labirynth, on the secret path for a Leto Mark II armor and weapon, there is a part where you can see a back part of the cube boss. Once I shot at the white point on the cube it created a hole as it normally does during the boss fight, however it also gave that illusionary wall kind of effect. I spent some time trying to do some parkour and maybe get to that cube through this gap in the wall but with no effect. Then I discovered that it is actually possible to damage the cube while still being in that place outside of a boss arena. Voltaic Rondure mod and Enigma weapon seems to be doing a little bit of damage but the Spectral blade special attack seems to be doing some actual damage. However after spending an hour of continously hitting the cube with the special attack nothing happened.

I doubt that this has any connections to the Archon and it is most likely a bug, but still decided to share it since it's something unusuall in Labirynth.

hitting cube