How do I get this body armour located in Tomb Of Ramses III?

Don't have a screenshot for you because I didn't feel like booting windows and finding the right savegame. However, to your back are some steps. Locate the red/white + Box upstairs and go right of it past the rightmost pillar (hidden doorway). You get into a room with some extra goodies which has a normal (non-hidden) passage to the balusters you can see from your current position (on the picture). Then you're practically there.

If this was still too fuzzy, I found a YouTube video that shows where to go exactly (everything is cluttered with text for some reason and it's black/white, but it gets the general idea across).