"Held on" is a phrase that implies maintaining a grasp or connection with something or someone, or persevering through a difficulty or challenge. If you're looking for synonyms for "held on," you might consider using words like "clung," "grasped," "held fast," "persisted," "endured," "persevered," "clung to," "hung on," "latched onto," or "clutched." Each of these words can help provide a similar meaning as "held on," but with a slightly different nuance or connotation. So, depending on the context in which you're using the phrase, you might find word choice makes a big difference in how your message comes across.