Blacksmith Vincenz:
Well, it's better to just try it for yourself. Here's a Practice StormBringer and a Practice Soul Crystal-Stage 1. You'll need to have a Gemstone that is appropriate for the level of the Soul Crystal. Now, I'll give you a Practice Soul Crystal Gemstone, but next time, you'll have to obtain the Gemstone yourself.
You can purchase Gemstones from the Traders at the Store in the Village. There are various Stores in the village and each trader sells different items. It'll be good to know about their items.
If you want to try a Soul Crystal ability with other weapons, you can always try it out.