Let's take a look at the symbols found on her chest:
The top one is Neptune and/or a trident with lots of meanings. The bottom is simply the alchemy sign for glass. Haven't found any deeper meaning for the glass symbol, but will continue to keep my eye out for something.
I'm pretty sure the symbol you see on the right is for Reiki Energy, used for power and energy flow - which may be just what a witch like Rowena needs to cast a spell.
The mark on the left is a bit harder to track down. One random web site said it was for making dreams come true and attracting success but didn't have a name for it. I did find something similar in a listing for protection sigils. Notice is also has a trident in the middle!
And one bonus Rowena symbol!
And now we know that Rowena (or at least the art department) is a fan of Prince! Pretty good lol SPN!