Melee:
1. Dark Lance: Easy to find (once you go to the Underworld) and helps in exploration, and also providing defensive methods as well as light. Its piercing powers are very useful. Unfortunately, during the middle of a goblin army battle... my game crashed and the Dark Lance somehow disappeared.
2. Starfury: Projectiles easily help analiate most pre-Hardmode bosses and help exploration more than the Dark Lance
3. Flamarang: I saw my friend using this weapon, and decided to try it out myself. Collected a bunch of the crap needed to make it, and it paid off. Takes care of most enemies
Ranged:
1. Minishark: Farming bosses becomes so easy to do with this gun. I don't regret it at all buying this.
2. Star Cannon: I got angry at Lepus. Like, REALLY angry. (The thing just kept spawning more and more of itself, and I was stuck on top of a broken balcony, just trying to kill the stupid bunny with my Starfury and Flamarang, no good), so I put my Minishark into the Star Cannon, and tried to fight Lepus again. It failed miserably, but now I have a super-powerful weapon in my hands! I probably will regret it later on, but this weapon will definitely help me through Hardmode, so regret only comes temporarily
3. Phoenix Blaster
4. Iron Bow: I used this bow to kill a Queen Bee that refused to despawn. What a stupid glitch. I wasn't even prepared for the battle. I swear, I must have died at least 5 times, and the Queen Bee just didn't despawn. It literally wasn't funny.
Magic:
1. Fire Flower: I knew this was a good weapon from the start. I researched this in the wiki, and realized that this, the star cannon, and the Starfury will help make my life in Hardmode just a tinsy better.
2. Bee Gun: Saved my life several times, like the first time I was fighting Skeletron. Just kept dodging and letting the bees do their work.
3. Demon Scythe/Book of Skulls: I still don't know which is better
Thrown:
1. Grenades: High damage on impact. Very good.
2. Spiky Balls: Cheap and still resourceful
3. Sticky Bombs: Just because Bombs will blow up the landscape.