Guild Wars 2

Why does my Asura engineer not have a second set of weapons that I can switch to? To clarify, I don’t have a slot for a second weapon set.

Because Engineers, just like Elementalists, do not have a secondary weapon set at all.

However, you can use the Utility Kits (Grenade Kit, Bomb Kit, Flamethrower, Tool Kit, and Elixir Gun). They work similarly to Weapon Sets since they replace your weapon skills and they trigger effects from weapon swap sigils and etc.