When forging heavy slingbows and you roll the action speed defect, it doesn’t matter how much it levels it, it will reduce it to level 1 once you set it, which is -5 AS (because otherwise the bow would end up with 0 or less AS, which apparently the game doesn’t allow). Haven’t tested it, but my guess is it also wouldn’t reduce any of the other bows below 5 even if the defect was leveled enough.
Slingbows also can’t go below 0% crit chance, so rolling the defect on anything but ruby and diamond will do absolutely nothing!
Yup, even using an unchisel and chiseling again works. I found a level 5 meteorite from someone’s hunt today and beaconed it for fun since everyone was long gone, and decided to try, and so I found out!