[@Lunarlors34]

For something like magic, I was thinking something akin to Bending from the Avatar; while many of Re:Zero's magic can work without having a source (I'm pretty sure Rem simply materializes water and giant ice spears), manipulating an existing source of your element is far less taxing. Additionally, trying to manipulate or use more than what your skills would indicate would be harder, if not impossible for what you're trying to do.

Example: Vesta and another earth-magic user making a statue of themselves, fairly simple. Making a suit of armor out of solid rock that they can move and manipulate as they move, probably something only Vesta can do.