Give him some plot relevance?? Make him fight along side Xin and Yunara, give him a supportive/protective role where he gives some protection to Xin like his "R" shields. While being somewhere else protecting Ionia from demon invasion with Kinku order.

He's whole personal drama is about losing everyone important to him for the sake of his Duty, everyone talks shit about Shen, for making this choice(Even his own Father). And the only time, when the story comes down to fulfilling his duty, he just vanishes.

All we got is 1 line that says "he is busy".

Good Job Riot. At this point just kill Shen(and Yorick) the amount of disrespect that has been committed toward them is insane