I like to over analyze things and dive too deep into ideas that very likely weren't the intention or aren't really there at all. On the other hand, I view analysis as something that there isn't really a right or wrong answer to, so long as there's a compelling argument. Also bear in mind I tend to speak from personal experience with certain topics, so you may very well disagree with any ideas I present, which is fine! That being said, Powerless isn't about a failing relationship or watching someone close to you fall apart - it's about watching yourself fall apart.
The entire song is the duality of second and first person, indicating the protagonist is directly addressing some other being (wow what a deep thought). This "other being" is a characterization of depression or mental illness or whatever it is the protagonist is suffering from. The first verse sets up the dynamic between the two. As Heavy so accurately states "I wanna let go, but there's comfort in the panic". That idea is very present here. As mental illness is very much a part of you, it sees and knows all. It knows every aspect of your life, the positive and negative. You unwillingly open yourself up to it, and as time goes on, you become used to it being there. It becomes part of your routine, learning to deal with a voice in your head pointing out everyone of your flaws and mistakes. However, like Chester said in Heavy, there's a sense of comfort in that after dealing with it for so long. Any change to the status quo leaves us scared and uncertain, even if that change would likely leave us better off in the long term. So he clings to it. He "[wakes] the devil" inside because the thought of change is a terrifying. There's some very obvious self-harm imagery to close out the verse, as the "crimson soaking through" literally represents the blood from cutting, but also metaphorically just represents the history of what the illness is doing. The evidence is there, and the toll it takes on your mental health may not be physically apparent, but it's very prevalent to them. You promise yourself this is the last time you'll tolerate it, but, like I said before, it's much easier to cling to and revert to what you know than risk something unknown. Ten thousand promises, ten thousand ways to lose.
The chorus is simply the fall. There's almost a complete separation of the illness from the actual person here, pinning the fall entirely on the illness as the protagonist watches from inside his own head. It's a mix of feeling helpless and disdain, both for the illness, for actually doing it, and themselves, for letting it get this bad.
Verse two ties into the overall message of verse one a bit more but with a darker undertone. Even as he falls apart and feels that his life would be significantly better without the illness controlling his actions, he still feels the need to chase after it. That separation that was present in the chorus is undone here as the protagonist tries to maintain that status quo. Without it, he feels alone and scared, but with it, he feels useless. it's a toxic relationship, a push and pull that, no matter which side ends up winning, he loses.