to calm one self, leaving a fear behind, or to make something certain (see Molina)
Alonso de Molina:
yollo motlalia. no. (pret. onoyollo motlali.) asossegarse echando de si el temor que tenia, o satisfazerse delo que dubdaua. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 40v. col. 1. Thanks to Joe Campbell for providing the transcription.