"We can keep doing this for all eternity." Arnold mumbled while playing with a scalpel he had forged using celestial gold, "Neither you nor I will age even a second, and I'm not going to stop until you tell me what I want to hear. I'm having fun doing this too. After all, that bastard Hermes died before I could witness a god withering in pain."
He was talking to a naked Heimdall, who had been tied up to a chair using chains made of titanium. Considering the weak and pathetic state he was in, it wouldn't have mattered even if he was tied up using a single thread. Heimdall wouldn't have been able to lash out at his torturer.
On top of that, even if he could get free, what could he possibly do? He was inside Arnold's domain. Normally he could have contested the ownership of the domain using his influence, but in front of Arnold, Heimdall's existence was, in simple words, pathetic.