Whatcha mean by 'you can swap'?

The concept of any Silver special is that it's situationally useful. For a Silver Genre Special, you can imagine that it's something that grants a Rank up for either a certain type of spell or in certain circumstances.

As some examples...
Access the power grid and use Bend to increase the damage of spells by one rank.
Self-cast Speedster increases Damage by one rank as well, because robot overclock.