Weapons with condition effects have been changed so that they do not inflict Poison, Berserk, Sleep, or Stone when the damage dealt is 0.
In FE5, weapons with Poison and other condition effects could inflict these conditions when they did no damage as long as they hit. This was probably a design oversight, and was fixed in later series.
I don't know which title this was fixed in because I haven't checked, but at least in the newest FE Engage, Poison cannot be applied when the damage dealt was 0. This is how it should be.
