How about being the bearer of bad news (2 Sam. 1:1-16)? Or the husband of a woman of whom David took a particular fancy (Nabal/Abigail, 1 Sam. 25:1-42; Uriah/Bathsheba, 2 Sam. 11:1-24)
As for Abigail, God killed Nabal, David took haer as a wife after, not the same thing he did to Uriah.
He coveted Bathsheba, committed adultery and had Uriah hung out to dry in battle when he had been a faithful servant. Uriah wouldn't go home and sleep with his wife when his compatriots were engaged in a campaign. This meant David couldn't hide the sin from the people, so he had Uriah killed to get her.
Cruel, unjust, you bet. When confronted by Samuel, David repented and was forgiven. Not very pagan or brutal. Yet he was a king who waged war and warring without the use of stand-off weaponry is considerably more brutal than today even though the results may be similar.