There are three basic methods to sword counterweighting as follows:
One method of counter weighting sword is adding tungsten alloy sword counterweight to the pommel. This puts the weight as far away from the tip as possible, and is thus the most effective method per ounce of added weight of lowering the balance point. Downsides compared to other methods include aesthetic issues, durability, and relative complexity of construction. For a relatively small degree of counter weighting, simply incorporating a large amount of tape while constructing the pommel can help. For more dramatic counter weighting, tungsten alloy with high density can be built into the inner layer of the pommel.
Another method of counter weighting sword is placing tungsten alloy sword counterweight on the handle. This has the added effect of increasing the diameter of a sword's handle and is easier to construct and less likely to be ugly than pommel counter weighting. However, since the weight is slightly higher on the blade, it takes somewhat more added weight to the sword than pommel counter weighting to bring the balance down to the same point. The most common method for (extensive) handle counter weighting is to wrap wire around the handle. Tungsten alloy sword counterweight of various types can also be used.
Tungsten alloy core counter weighting is a method where a weight is added inside the handle of a sword with a hollow core material. Tungsten alloy core counter weighting has essentially no effect on the appearance of the sword and is a relatively easy way to add a significant amount of low-centered tungsten alloy sword counterweight to certain cores. However, there is usually much less control over exactly how much weight to add without sawing a large diameter metal bolt to a custom length or employing more uncommon methods.