Guild Wars 2

I have been doing some research on Engineers since it seems to have so many options, that I am curious what I should be aiming for In terms of what utilities to unlock etc…

I saw a Video on HGH build that suggests “on swap” sigils. I thought engineers were denied the option to weapon swap. How do the sigils procc?

Or do the procc when you go from Flamethrower to your regular weapon set?

Any help would be appreciated.

Yes this is correct. The procc when you go from Flamethrower to regular weapon.

Switching attunements as an Ele or equipping kits and stow them away counts as switching weapons as well.
It also counts as activating a heal skill when you equip Med Kit.

I want to thank everyone that responded, Now it makes sense.