Jamieson, Fausset and Brown on 1 Chronicles 10:10

10. put his armour in the house of their gods--It was common among the heathen to vow to a national or favorite deity, that, in the event of a victory, the armor of the enemy's king, or of some eminent leader, should be dedicated to him as an offering of gratitude. Such trophies were usually suspended on the pillars of the temple.

fastened his head in the temple of Dagon--while the trunk or headless corpse was affixed to the wall of Beth-shan (1Sa 31:10).