I've been using some courage stones... actually way over 10 of them. 7-8 succeeded but none of them had any impact on the weapon (0% -> 0%).
Q1: So, should I just keep trying or is it possible that the item just doesn't like courage stones at all?
Q2: Originally the sword had +6% phy pwr but assimilation took that away, maybe that's the reason why the stones won't work?

Q3: This is how they normally work (a ton of stones just to get the % change once and god knows how many to get a reasonable %)?