Use what you have available for the particular contour you need.
I like to use powered tools in the initial shaping, then finish by hand.
Best to use a bandsaw for as much as you can first.
For shaping handle material by hand, different shapes of rasps and some shop-made radiused sanding blocks are hard to beat. Cutting as much of the shape beforehand with a bandsaw makes it go quicker and saves some armwork and abrasive.
For profiling the metal, various sizes of both round and half-round files work well if you don't have access to a contour saw (metal-cutting bandsaw with a narrow blade).
The rotary tools (Dremel, etc.) are great for small detail-type work. Use of a good knife vise makes the job easier.
These tools were not designed for heavy loads, so take it easy if it's all you got to do major shaping. Keep the pressure adequate but not too heavy and let the abrasive do the work or you'll burn up the tool.
(On one of my buffing units, I have a flexshaft. Considering the motor for the unit is 1 HP, I'm not gonna hurt it!)
The belt sanders are, IMO, the quickest. Slack belts work well for rounding over, "blending things in", and fair curves.
Small contact wheels of appropriate diameter work best for actual hogging to establish the profile of tighter curves and radiuses. They are especially effective at profiling the metal.
If you are not set up for the small contact wheels, don't overlook the use of various sizes of sanding drums in a drill press. These will have the same effect as using the rotary tool, only faster and less tiring (to me, anyways).
No matter which method you use on the power tools, it's probably best to leave a little room for final work by hand.
Good Luck,
Rob