Explosive Shot...
probably for balance issues.
Possible balance issues and probably different teams not communicating to avoid, say, misleading skill descriptions that seem to indicate that certain traits should function with them.
It is important to know the difference between fluff language and game language.
You want the skills to read like they flow together. An elixir gun, for example, fires elixirs.
But, you want balance too. If an elixir gun’s elixirs are treated as elixirs for trait and skill purposes, you would have some real balance issues. You wouldn’t have to trade a kit for a single purpose utility slot. You would have so many more elixirs for might stacking. Etc.
I do think it helps to have it clearer what language matters in terms of game mechanics.