The second chance to obtain Trine in “Final Fantasy VII” is in disk 2, against an enemy called Stilva, which looks similar to the Materia Keeper, which can be found after climbing and traversing the snowy mountain and entering Gaea's Cliff.
By this point it can be learned on three of the four Enemy Skill Materias, however to learn Trine on the final Enemy Skill Materia from the Chocobo Sage's house, the player must resort to the final option, which if done previously, completely shuts down the player's chance of ever learning the skill on the fourth Materia. The only place that Trine can be obtained with the fourth Enemy Skill Materia is the pagoda in Wutai, via a side-quest involving Yuffie.
She must fight through a boss-type enemy on each floor of the five-tier pagoda and challenge her father at the very top, all the while receiving absolutely no help from her friends and companions. Upon battle with Yuffie's father, he becomes a man with a four-sided head, and each side was associated with a certain type of action, such as physical or magical. This boss will occasionally cast Trine, and if Yuffie is equipped with the fourth Enemy Skill, then she will be able to learn it.
After the fight is over, however, it cannot be re-done. Meaning if the player forgot to equip the Materia, then it is impossible to learn Trine on that Enemy Skill Materia. The same goes for if the player had completed the side-quest prior to visiting the Chocobo Sage and receiving the Materia from his Chocobo.