I've read a good number of rust effects tutorials, but here's a really simple one when you have a tabletop army of greenskin axes and pole arms to paint.
* Wash weapons with brown Strong Tone Ink.
* Mix Army Painter brown Strong Tone Ink with a little orange Dry Rust Effect, and a little red Crusted Sore.
* Dab onto the edges of the weapon blades.
Done. No stippling, layers, or whatnot. I've noticed that blood has to be painted differently depending on if it's fresh and dripping, dried and caked, etc., so I'm not surprised that this way to apply blood and rust differs from other rust effects for rust painted differently.
On the table, you don't need anything fancy, but you can still get blood on those dirty axes in seconds.