[masaegu]

～～でいるわ　＝　～～でいます = I will stay as ~~.

We just don't use だ nearly as often as they appear to teach you outside of Japan that we do. If you said 織姫だ, it would sound to a Japanese-speaker like you're being either too manga-influenced or too aggresive.

These little sentence-enders can give your sentences so much character, which is why they are useful and at the same time why you cannot choose the wrong one. In other words, they can cause you to end up sounding like a different person.

わ is a nice-sounding assertive sentence-ender. You can use it quite often but not repeatedly. Use it repeatedly and you will sound like a very self-centered person. For that matter, do not use any single sentence-ender repeatedly or you will sound like an anime character.

Girls may use わ more often but men use it quite often as well. I'm male and I use it pretty often in casual speech.