Lol! I think it is a magnesium alloy that is nonreactive to water. I have seen a few knives with “magnesium” construction. Otherwise it would bring a whole new meaning to the term “hot spot” when you sweat on the handle and it burst into caustic flames.
Lol no, aircraft grade aluminum is a specific set of alloys which are much stronger than other grades of aluminum while maintaining it’s characteristic lightness. I believe there are a few different grades of aircraft aluminum but either way it is very strong when compared to some other aluminum alloys. It’s not just a marketing term, aircraft grade actually signifies a specific alloy of aluminum unlike surgical stainless which specifies nothing other than usually a crappy knife steel.
There are other types of aluminum alloys which give excellent properties for lightness and strength such as Duralumin which was also used in aircraft. Rockstead used to (and I think still does) have knives with handles built lf duralumin.
If you’ve ever handled a strider (especially an smf) with two titanium scales and that titanium backspacer the thing is a friggin brick. Using an aircraft grade aluminum frontscale was likely decided upon so you could get an all metal strider without it being a friggin boat anchor.