DM's: Focusing on character weaknesses ethical?

[Ridley's Cohort]

Yes, and the DM's job is to make sure all the players have fun. So if one character is outshining all the others because of a specific build, it is better for the game and enjoyment of the players to attack that player's weakness sometimes.

Sure. Generally speaking, making sure that all PCs get their moment in the spotlight and perhaps occasionally leaning on certain PC weaknesses to push them out of the spotlight, I would call that focusing on both strengths and weaknesses of the PCs as a group overall.

BTW, it is not unfair in my book for the enemy spellcasters to after the guys with heavy armor who look like Fighters or the guys in light armor who look like Rogues with the Hold Person spell. That is the bad guys properly targetting dangerous people who are likely to have weak Will saves. And my DMs are very fair about it -- when there is a Paladin in the party the enemy spellcasters do not know to avoid casting spells on that PC.

 

[Mercule]

A bit of both. Characters have strengths that should allow them to shine. They also have weaknesses which make them human(ish). More time should be devoted to their strengths, but the weaknesses should not go unnoticed.

It should not be done exploitatively or vindictively, though.