Filter
Binding spells are not dark. What makes something dark is partially about the effect of the spell - although dark spells definitely have worse effects - and more about the intent required behind them. To use the forbidden Cruciatus Curse, you really have to want to put someone in extreme, debilitating pain.
The stinging hex we use - not the same as the rope binding one - does hurt a fair amount, but it's more like having a really bad reaction to being stung by a bee, instead of literally every nerve in your body being on fire.
This really isn't as complicated as you're trying to make it seem.