Courage is a bit to strong and they are thinking about nerfing it. Making it stronger for 1v1 is also not good because some champions are a bit to strong with it. Personally, I don't think its too op but I do agree with lowering it down a little bit. I saw some people suggest to just lower down to 5% Max hp instead of 7% and I feel that is a pretty fair idea.
That way it would be 5% + the base in 1v1 and when you are in a 5v5 team fight it'll be 25% instead of 35%. (I know you suggested 25% at max as well, but this just feels easier to do plus you suggested to buff it's 1v1 power which might be a bit much).
Other suggestion I saw was to increase the base even higher, but make it Bonus %HP instead of Max, which I could see that being an option, so we don't see non-tanks abusing it.