Irresolution is the lack of deciciveness or purposeiveness. Irresolution plagues Hamlet when he cannot decide whether to believe in the ghost and act on the ghost's demand for revenge or not. Irresolution plagues Doctor Faustus when he cannot determine to break the shackles of Mephistopheles hold upon his soul and beseech God's forgiveness regardless of the soul-wracking pain the attempt will bring him
Dramatic strength encompasses many elements of dramatic technique, not the least of which are characterization, dialogue, plotting, diction and other devices, and imagination. In short dramatic strength is measured by how thoroughly no element(s) distracts from the effect of the drama or from the passion of the play.
The irresolution that plagues both Hamlet and Doctor Faustus adds dramatic strength in both Shakespeare's and Marlowe's play. In Hamlet, Hamlet's irresolution is part of the rising action and contributes to authentic turmoil and ingenious means by which to get at the truth of Claudius's guilt, specifically the play within the play of Act III, scene ii.
In Doctor Faustus, Faustus's irresolution is part of the falling action and leads right into the resolution. In this phase of the play, his irresolution adds to the painful suspense of "Will he? Won't he?" which builds a cathartic anguished feeling in the audience when it is seen that Faustus does not withstand the pain and confess to God.
Thus it can be seen that in both plays, irresolution, though used in different places and for different purposes, produces dramatic strength in characterization; in passionate feeling; in plotting; and in the unity of dramatic elements.