Over the years, I've had many swords I've trained on, light and heavy, good quality and poor, well balanced and poorly balanced, steel of different tempers, and wood. I never felt a decently weighted Chinese sword for the first several years, using only wood practice swords, steel pipes, and a medieval European replica, serviceable, but not ideal, for Chinese styles. (Swordsmiths have to forge for specific purpose.¹) For a couple of years I was even using a rod I cut from a sapling to try a little Japanese two handed cutting. Even now, when you can get great steel from China, heavy and light, I wouldn't say any of my blades is exactly perfect, balance wise, just better then most, and well good enough.
Now that I have better swords of all weights, I rarely practice with rods or poorly weighted weapons. I don't typically use my decent wooden jian trainer, as an example, even though the action that used to feel non-existent when the wood felt heavy, now feels better than some steel I've worked with, and better than a rod, if less significantly durable.
- Is it important to practice with poorly weighted blades and sword analogs?
Answers from any perspective and dimension of the question are welcome.
 Sprague, M., Longsword and Saber, 2013. "A skilled swordsmith was therefore familiar with the particular fighting techniques the swordsman could expect to encounter."