Ok, as I mentioned before you need a steel that exceeds the hardness of your knife, or the knife will shave the steel bald and you don't want that. Given time using a steel, because the angle you use it at is unlikely to be exactly at the angle the knife is ground to, you will wear the ground edge down and you won't be able to get a nice edge with the steel any more. You'll then need to regrind it with a stone, which may be the stage where you have got to with a steel.
The thing to remember here is any whetstone method restores the shape of the ground edge but over-use will wear the blade down prematurely. Use a steel most of the time and only use the stone when you have to.
I wondered if the 'recommended for Global' thing was something to do with the angle but in the instructions it says that other knives can be used but may need more passes than Global blades do.
The thing to remember with a whetstone is you have to be able to grind the edge at a very precise angle which either takes a lot of practice or you need a guide. I decided to go for a system that already sets the angle, hence the MinoSharp block is quite good for me.
