It's a person who can be objective, while still seeing the wider view.
I think an engineer must be open-minded and have many fields in which they are skilled, and where they're not skilled they should be able to find the skills needed.
It's something other than a technician. A technician is the technical sort, they know their machines. The engineer doesn't need to. That's not their job. It's not to know the machine, it's to guide the person who knows the machine.
It's someone who knows how to look, listen and analyse, and make suggestions according to all that.