In terms of skill in Tai Chi it is all relative. This means that the better you can do something than the other person the more you can feel what the other person’s skill is like.
For a long time X’s hands are like the unsettled rooster in Zhuang Tzu’s story of the Fighting Rooster. At the slightest touch X’s hands would resist. It took years of training before he let go of his strength more and become less resisting and more settled enabling him to adhere and listen better.
Now X has reached a level where he said when he felt Y’s hands he could feel it resisting and he could use the resistance against Y. Before when X’s hands were strong and resisting he would not be able to say this because he can only use strength to overcome a weaker person.
With the passage of time he can feel another person’s hands so much better, so much so that relatively speaking the other person, in this case Y, seems to be resisting a lot. This is why in learning Tai Chi time put in leads to the acquiring of kung fu, meaning you can makes theories and debate all day and all night long but without putting in the practice over years the skill won’t grow.