I don't think it's technically correct to say that the US armed ISIS; ISIS seized weapons that the US provided to Iraq.

Israel does a pretty good job of opposing Iran, and we can be confident that weapons provided to Israel aren't going to be used against the US. I think it's likely that the Houthis are acting up now not because they're provoked by Israel but because Israel is preoccupied with something else.

As for Saddam Hussein... He did a very good job of opposing Iran. The threat of eight years of war and hundreds of thousands of Iranian soldiers dead would be a very effective stick if we still had access to it. It's ironic that the weak, pro-Iran government that is the result of US intervention in Iraq seems like it's worse for US interests than Saddam was.