Here is what I use to hold the blade for sanding.
To Hold the sand paper , I agree with Thomas, use the right block for the job. I use lots of different blocks, running from rubber to plastic, and wooden paint stir sticks to polished Steel barstock, round or square soft or hard. I find that a sanding block foot long or so wrapped with paper in the middle, can be used 2 handed and really works fast.
Jens