I haven't played the inspirations, but I am interested. I do have a question though, what is this significance of this "Wearing a Semblance allows the absorption of that essence." ?
Thank you very much for your interest!
To answer your question;
The Semblance is the essence of a fallen entity, be they Enlightened or Unfettered, gathered by the Semblance Caretakers and forged into a Semblance/Mask. It's the literal crystallization of a Fallen (I may start using that term for those who become a Semblance) into a tangible form. The Semblances are interred in the Crystalline Garden to protect them from being used in just such a way. Any entity that is not an Enlightened or Unfettered that chooses to wear a Semblance forms a bond with the essence it is composed of. The 'host', once this bond is formed, begins leeching away at the Semblance and drawing it into themselves; whether they intend to or not.
The significance of this is that it imbues the 'host' with the abilities that the Fallen once possessed. Normally, those abilities would only be usable in the 'other world' (Irriss, for those curious); in this case, though, the absorption of the Semblance will have a profound influence on the Player's Character. Which will begin with their arrival in Irriss.
While wearing the Mask in Irriss, the Character will be given a different appearance; one that is a mesh of the Fallen's and their own psyche. This will last until they return to Lightbridge, where the Semblance will be completely absorbed; essentially merging with the Character's soul. This is where the Character's changes will begin.
I'll be leaving the design of the Semblance and the Fallen it was forged from to the Player. So, how the effects will come about will be up to the Player.
I hope that was an adequate response. If more information is needed, I will provide it!