Here is the full list of all 29 Fairy Fencer F achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
You saw the normal ending. "Yeah... Take care."
Boosted one of your weapons to its max. "With this, your combat strength has increased drastically!"
Dealt 100,000 damage. "With this one blow!"
Cleared all 40 floors of Shukesoo's Tower. "Mwahahahaha!!"
Pulled every sword from the Vile God and Goddess. "It took a long time but we're finally finished!"
Sealed the Vile God using Godly Revival. "Time to seal you away for good!"
You saw Tiara's ending. "You have changed everything for me."
Lola joined the party. "Despite my appearance, I'm actually a fairy."
Apollonius joined the party. "I'll become your overseer."
You saw Eryn's ending. "I'm hungry, too!"
Fought 500 battles. "Fwoooooosh!"
Performed 100 Avalanche Attacks. "We're invincible!"
Maxed your tension 300 times. "I'm fired up!"
Accumulated 20 hours of playtime. "That sounds like it'll take forever."
Performed 100 Air Combos. "There!"
Performed 250 Hits. "I'll...cut you...to shreds!"
Reached level 10 with one of your fairies. "There's still much we don't know about fairies."
Eryn powered up. "If I decide to get serious, I'm capable of all kinds of things."
You got sent to an unknown place. "Eryn, wake up! Where are we!?"
Fought 200 battles. "I didn't realize I was so strong."
Fought 50 battles. "This is nothing!"
Boosted your weapon for the first time. "This is simply the first step."
You became Eryn's Fencer. "Nice to meet you, Fang."
Obtained every trophy. "Thank you... I love you."
Defeated 10,000 enemies. "There's no way I can stop!"
Reached level 99 with a character. "My coolness is about to reach godly levels."
Reached level 99 with every character. "They're calling themselves a hero's adventuring party..."
Achieved a Quest Rank of S. "...I shall continue counting on you."
Accumulated 100 million G. "As usual, I smell the fragrant aroma of money coming from you today!"