Note to Hamlet, 4.7.76: "Of the unworthiest siege"

Act 4, Scene 7, line 76
Of the unworthiest siege: i.e., least important.  —The king, using his wicked silver tongue to manipulate Laertes, tells him that he shines for one quality, but a quality which is the least important of all his good qualities. Thus the king both flatters Laertes and whets his appetite for the revelation of the quality which the king is alluding to.