Cool But Inefficient has these relationships to other tropes:

parents kids shares a parent with:
Power Up Letdown
Bling Bling Bang
parent child
Powerup LetdownUseless Useful Spell
Power Up LetdownBonus Feature Failure
''Awesome But Impractical
''Promotional Powerless Piece Of Garbage
''Scrappy Weapon
You'll need to Get Known if you want to add or modify these relationships.