Nathan the prophet delivers a piercing rebuke that strips away any illusion of innocence from David's actions. While a person might find earthly legal justifications for their behavior, the ultimate measure of right and wrong rests with God. Because God had granted David so many blessings, ignoring the divine command is considered an act of deep contempt [מצודת דוד]. The traditional reading of the text emphasizes that this wrong was committed directly in God's sight [מנחת שי, ביאור שטיינזלץ]. Therefore, even if David could have successfully defended his actions in a human court of law, his deeds remain evil and entirely unacceptable to God [מלבי״ם].
The accusation of murder is leveled squarely at the king. Even though David did not strike the fatal blow with his own hands, he bears the full guilt because he issued the order to place Uriah in mortal danger [מצודת דוד, רד״ק, ביאור שטיינזלץ]. Normally, legal responsibility for a crime falls on the person who physically commits it, rather than the one who ordered it. However, the rules change when dealing with a monarch. Since a royal decree is absolute and subjects are terrified to disobey, the king’s command functions as a direct extension of himself, making him the actual murderer [רד״ק].
The guilt is compounded by the specific method of death. Using the sword of the Ammonites points to a sin far worse than if David had simply killed Uriah himself [מצודת דוד]. Lacking the courage to execute Uriah openly, David resorted to deceit, orchestrating his death from the shadows [ביאור שטיינזלץ]. This added a separate layer of evil, as David intentionally handed an innocent man over to the enemies of Israel [רד״ק].
Ultimately, the taking of Uriah's wife and the orchestration of his death are not separate events; they are tightly bound together as cause and effect. David arranged the death on the battlefield with the specific goal of making Bathsheba his legal wife. Because the marriage was only possible through this orchestrated death, the battlefield casualty transforms into premeditated murder, and the subsequent marriage becomes an act of outright theft [מלבי״ם].