As I've mentioned before, the best way to build strength is with relatively higher weight and lower repetitions. For small joint exercises we can't get too high an intensity, but it is safe to do exercises in the 10-12RM range for the wrist; and elbow exercises in the 8-10RM range. Therefore increase the weight of the tool until you can only do the specified number of reps. This is also the reason that I prefer an adjustable tool.
This is in distinct contrast to the usual program for these tools which is based around very large numbers of repetitions at just a few pounds. This style of exercise will produce gains in muscular endurance but very little gain in strength. For somebody new to the program there will be a noticeable gain in strength when starting this program, but these gains are primarily a result of neural training. The training effect is that the muscles become more efficient and coordinated at the action. While this isn't a bad thing, it's not the result we are looking for in strengthening the muscles, because we still aren't triggering or building up our high-threshold motor units. The high-threshold motor units are responsible for our strength and power.
Further we should avoid trying to have good cutting form with these tools. It's not possible and so we shouldn't. Trying to have good form with a strength training tool will cause us to distort our form and so degrade form in the long run. In general you should not try to train form in a tool that weighs more than double the usual amount. For a tool that we are swinging around the math requires an extra step because we are looking at moment of inertia*. In short multiply the total weight of the tool by the distance from the top of your hand to the center of balance for the tool. For a typical longsword, with a 10cm CoB and a total mass of 1.5kg we get .15kgm. With a 2.5 kg tool (~5 lbs.) that's built like a clubbell the CoB is around 20cm out. As such we get a moment of inertia of .5kgm. Too heavy for good form. So use this tool for strength training instead.
* I have simplified the physics here for the sake of making it accessible and usable for a large number of people. I do not believe that my simplification alters the utility of the math.
Wrist and Elbow ExercisesMoulinets and Falling-away - lie on your back* and extend your arm straight up. The imaginary target is in the direction of the ceiling. Cut wrist moulinets: inside, outside and reverses. To make the exercises more difficult you can fall away to the same side, that is when cutting an outside moulinet have the weight fall to the outside instead of continuing in a straight line to the inside.
These exercises are done with the forearm straight up so that the "power" part of the exercise is with the weight moving away from you and towards the target. Normally these exercises are shown standing upright with the forearm parallel to the floor. In that position the power is on the return action and the weight can fall through the cut.
* You can also stand/sit with the upper arm parallel to the floor and the forearm straight up, but this brings the weight closer to the head, so it doesn't work well with a lot of equipment or is just plain dangerous.
Disengage - assume the same position as above and then simply make circles with the end of the tool. Small circles are easier and more specific. Larger circles will require and build more strength but are less specific. A mix of each is reasonable. Remember to do both clockwise and counterclockwise.
Elbow Cuts - from the same position you can perform elbow cuts. For these actions a larger weight will be needed to maintain a strength training stimulus. And lower reps can be safely done because the prime movers are the elbow muscles. This exercise brings the weight closer to your face so care must be taken to avoid injury.
Wrist Abduction and Adduction - Stand upright with your hands down by your side palm inward. Let the weight hang down and then lift it straight up. This is the power stroke of a false/short edge cut. Then reverse the weight so that the heavy end sticks out from the pinky side and do the same. This is the power stroke of a long/true edge cut.
Wrist Supination and Pronation - Stand with your arm extended fully out in front of you. Stick the weight out perpendicular to your arm, to the inside and let it hang down as far as comfortable. Then bring it upright. The next exercise is to rotate the end around until it sticks out to the outside line. As the pronators are normally stronger than the supinators it is necessary to switch weights for these two exercises.
Wrist Extension and Flexion - These exercises are done with a dumbbell. They consist simply of standing with the arm hanging at your side and curling or extending the wrist. They can also be done seated with the elbow on your leg and the forearm parallel to the floor. This produces a different stimulus, so it is useful to occasionally switch from one to the other.
The wrist curl will also help develop grip strength for grappling.