Dormin says the following upon retrieving the item:
|“||That is the 'Harpoon of Thunder'... With it, thou shalt be able to inflict greater damage upon a colossus from afar...||”|
The damage done by a fully charged throw is about the same damage as a full stab with the Ancient Sword or the Sword of the Sun. Even though it deals serious damage, the Harpoon is still a ranged weapon and thus cannot kill a colossus. A colossus' life bar can be almost depleted with the use of the Harpoon, but in the end a stab from a sword is still required to kill it. It will, however, like the swords and Flash Arrows, trigger minor sigils with a successful hit.
- The reticle seen while aiming the Harpoon of Thunder is different than that of the bow in both color and shape. It is green and more circular.
- In the PS4 remake, the Harpoon of Thunder is able to actually kill some of the colossi, as demonstrated in the following videos: Phaedra, Dirge, Kuromori, Argus, and Malus.
- Wander can be seen wielding the harpoon in the concept arts of both Hydrus and Pelagia, suggesting it might've been more integral to the main game early in development.