I have just started playing with harpoons and have found a bug regarding the stun mechanic.
So, in normal use, a harpoon reduces attack by 20%, and, if used on a stunned Titan, the defense is also reduced - all good.
However, I have discovered that if you stun a titan using a Tornado item, by having the tiles cause a stun during the reshuffle, and then use a harpoon, it does not give the stun bonus for the harpoon. It treats the hit as if made to an unstunned titan.
As you can see clearly, I use a Tornado, and the tiles reshuffle and stun the titan, however, when the harpoon is used, it acts as if it was not.
Thank you for your time.