30-45 degree "blade angle": is this the angle of the blade, or the handle to the skin

I am not exactly sure what I have heard on this forum and Mantic's videos regarding the "blade angle". Is this the angle of the blade to the skin, or of the handle of the razor to the skin? It would seem from the name of it that the former would be the case. However, this can be rather confusing, because if you started out with the handle perpendicular to your skin, and you rocked the razor 30 degrees downward, this would give you an angle between the blade and the skin of 30 degrees, although the angle between the handle of your razor and the skin would be 60 degrees. I only ask this because it seems to me that when trying to find the perfect angle, it would make more sense to describe it as the angle between the razor handle and the skin (60 degrees), rather than the angle between the blade and an imaginary line perpendicular to your face (30 degrees). Tell me if I'm looking way too much into this.

(sorry, I'm a math person )

There are a lot of threads on this topic if you do a search on blade angle.
If you haven't already looked, start with this one

Think of it as a blades angle of attack. This may be different from razor to razor as well. I recall a discussion about the differences in razor angle a Gillette Super Speed had compared to a Merkur HD that was helpful for me as I like both of these tools and find I hold them very differently.

ah, right. I somehow forgot that the blade is bent when in the razor.

A word of advice ... don't worry so much about it. The face has too many contours to keep a perfect blade everywhere. You'll know if the angle you are using is correct. If you are unable to shave a particular part of your face correctly then the angle is too steep or shallower. Try a different angle. I think the blade angle discussion is important to get a ballpark idea of what angle to use. The angle is weird if you came from the cartridge world, so again, it a place to start.

I scientifically determined the angle to hold the razor at to be exactly 45 degrees, for an HD at least.

But the easiest way to go is by paying attention to the feeling of the head being flat against your skin.

When in doubt, check the owners manual. Mr_Razor has a collection of instruction sheets that came with the Gillette razors.

http://mr-razor.com/Anleitungen/Gebrausanleitungen.htm