In the dim light, he grasped my hand firmly, refusing to let go.

grasped 是动词 grasp 的过去式，grasp 的意思是"抓住、紧握"，通常指用手紧紧握住某物或某人。这个词强调抓握的力度和决心，比简单的"hold"（握住）更有力量感。