There's a bunch of weapons you'll be able to get through various methods throughout the game, you'll need to collect them all.
Here's a list of them all so you can collect them all like Pokemon (Use Ctrl+F to find a specific weapon if you know it's name)
Nameless Blade - You start with this weapon you dingus ;)
Lily-Leaf Sword - Only 2400 from the Village Blacksmith
Nirvana Dagger - You'll find this at the Shrine, it will be inside a crate you can't really miss along the way up, just smash the crate and pick it up.
Moonrise - Early game you'll be told to go to Seafront for the first time and on they way you'll save a man under attack and he will give you this
Rebirth - You'll get this after completing the Barren Temple for the first time
Earth Wyrms Sword - This will cost only 8400 at Facades Blacksmith
Beastbain - This will cost a slightly more hefty 16800 at the Village Blacksmith
Blade of Treachery - At the Mansion you'll find this in a crate after being attacked by shades, you'll likely smash this crate while fighting them
Faith - Later on in the game you can buy this from Aerie Blacksmith before Aerie is destroyed for a slightly hefty 18500
Phoenix Dagger - For a nice chunk of money (31200) at Seafront Blacksmith, worth it though.
Labyrinth Whisper - Awarded for completing a quest given by a Village guard requiring you to kill a shade in the plains.
Iron Pipe - Awarded for Ending B
Ancient Overlord - Given in Facade as part of the story
Kusanagi - Awarded later in the story when you have access to different weapon types
Axe of Beheading - Bought for 19200 in the Village Blacksmith
Fang of the Twins - Under the Mansion you'll find a hallway leading a small-ish room with the weapon
Vile Axe - Bought for 21600 at Seafront Blacksmith
Beastlord - Near the boss room in Shrine inside a crate
Iron Will - Given at the Junk Yard as part of the story
Phoenix Sword - After the "point of no return" message there will be a crate in a garden by the door, smash it and take the sword
Labyrinths Song - Awarded for a quest given by the King of Facade requiring you to clear out the Barren Temple
Transience - Awarded later in the story when you have access to different weapon types
Spear of the Usurper - Bought for 21600 in Seafront Blacksmith
The Devil Queen - When you approach the Shrine by the rear, after climbing it will be in one of the crates
Sunrise - 21600 at the Aerie Blacksmith before Aerie is destroyed
Beastcurse - Before you fight the boss in B2 route of Junk Yard smash the crate beside the hole in the ground
Captains Holy Spear - A nice round 30000 at Facade Blacksmith
Dragoon Lance - After escaping the boar like enemy in the endgame you'll find it in one of the crates in the hall
Phoenix Spear - Probably the best weapon to use, 32400 in Facade Blacksmith
Labyrinths Shout - Awarded through a quest by the Village Blacksmith