Here is a point to think about..
It seems like without exception everyone in this thread is talking about the actual, theoretical or supposed effects of smoking herb on your aikido/martial practice.
Maybe that's backwards.
Maybe instead of the weed (or other things) making aikido richer or more interesting..
... maybe doing aikido (ukemi or various solo practices) can be something to make your use of the herb more interesting.
I know lots of people who like to smoke up and do tai chi. Most of them also do tai chi when they aren't high. They aren't smoking weed to make their tai chi better (or worse). They enjoy smoking weed and the tai chi is something like music or sex that's fun to do while they are high.
I know people smoke up and do yoga and hiking for the same reason. The yoga or hiking is something fun to do which enriches their pot-smoking.
Ask not: will weed-smoking make my aikido better.. rather ask.. will aikido make my weed-smoking better?