Machete's are fairly cheap tools, and the steel generally on the soft and flexible side. I've used sanders of all types in the past to remove rust and dirt and to get some type of edge back on my gardening tools and the odd machete. I wouldn't on a best tool. Sanders are fine heat wise but best if you run them at slow or medium, keep them moving, and don't put too much pressure on them,
A hand held belt sander at leasts runs in one direction. Oscillating sanders scrub material away. Both aren't a bad way of removing material though may not give a very flat result. Best results with old sandpaper grits, or buy some finer types, or even car paint prep grits. You can get buffing pads too but they get messy and are another expense. Sanders really are for old tools to give them another lease of life, so does it really matter?
Do whatever you feel like. Get a working bevel with the sander, secondary edge, and do the final sharpen by hand on large bench stone. Machete edges need doing often.
If you achieve a working edge and don't heat it to death then its good to go. Machetes take damage and are meant to be gradually sharpened away; takes years. If worn out buy another for they are cheap.
Your sander is every bit as good as some river stone that many a working machete is maintained on. They don't need a £££££$$$$$ sharpening system.
Its angle grinders that cut and destroy blades, and are the wreckers of whatever they touch.
