Hush Dart
The Hush Dart has a reported linear upgrade path that improves its effect and ammunition; repeated use over multiple dives can unlock its blueprint.
How it works
IGN says the Hush Dart follows a straight-line upgrade path and that each version gives a better effect and more ammunition. VG247 names it as a secondary weapon example and says using a new secondary weapon during multiple dives eventually unlocks its blueprint in the Weapon App. The sources do not detail its exact effect, ammunition amounts, levels, or required number of dives.
Read the supporting references
A source-bounded reference to reported diving gear effects and named weapon upgrade paths, including prerequisites and progression rules. Staff skills and restaurant upgrade effects are outside the retrieved evidence. Guidance explains the referenced mechanics; it is not a tested damage ranking. Check the stated edition and source version before applying a patch-specific detail.