I realize this is an old thread, but I just stumbled across it and here is my humble opinion.
Yes, invest in as good a hand saw as you can afford.

Over time, a good saw (kept sharp) is worth having in the toolbox. There are thing that a power saw just won't do and the hand saw will.

As to the grinder, I use a 5" electric with a sanding disc and 50 or 80 grit paper to "touch up" tenons and "break edges" and find it faster and more controllable than chiseling or planing the radiused corners of tenons prior to final fitting. It is fast, but be careful with the dust and keep it moving all the time it is touching wood or the results may not be what you would like them to be.

I wouldn't use it where the sanding marks are visible or the time you just saved will be spent cleaning up the grinder marks.

Oh ya, wear gloves, glasses and a dust mask...