The only line that looks similar to what you are asking is found in Act III, Scene 1. There, the Duke asks Valentine a question and Valentine answers with:
Please it your Grace, there is a messenger
That stays to bear my letters to my friends,
And I am going to deliver them.
In this case, "please it your Grace," or "may it please your Grace" simply means something like "if it is okay with you" or "if you will give me permission."
In this passage, Valentine has just come on stage and is in a hurry. The Duke asks him where he is going in such a rush and Valentine tells him. He says that he is hurrying to bring some letters to a messenger. The messenger is waiting to bring the letters to Valentine's friend. The line "please it your Grace" is simply a way for Valentine to be polite and deferential to someone who is superior to him.