why didn't vriska's dream self die when she lost her arm in the waking world? i mean, she didn't die in the waking world because equius gave her a prosthetic, but she didn't get one on prospit, so shouldn't she still have died there?

The wounds only seem to appear when you’re actually dying, not when you get any minor wound. Besides, the wounds on the Dream Self are a reflection of those in your Normal Self- If she just. Doesn’t die in the Waking World, there’s no reason why her Dreaming Self would die. Same way the wounds would reflect, so would the healing.