A hemostat-type device for ablative treatment of tissue, particularly for treatment of atrial fibrillation, is constructed with features that provide easy and effective treatment. A swiveling head assembly can allow the jaws to be adjusted in pitch and roll. Malleable jaws can permit curved lesion shapes. A locking detent can secure the jaws in a closed position during the procedure. An illuminated indicator provides confirmation that the device is operating. A fluid delivery system simplifies irrigated ablation procedures.