The disadvantage of the belt sander is that the edge of the belt is ill defined- it can be all over the place- so it is then very difficult to create some tool shapes. The edge of a grinding wheel can be maintained with a a diamond dressing tool and can be far more precise. The cost of an entry level grinder is less than the belt sander mentioned.
A diamond dust card is also very useful for touching up the cutting edges between sharpenings.A handy intro is ” Tool and Cutter Sharpening” by Harrold Hall number 38 in the Workshop Practice series.
I do have several belt sanders as well as bench grinders and a T & C machine, never use the belt sanders for tool sharpening but they are very useful for all kinds of shaping jobs.
Regards,
Alan.