Again, these all require that you have purchased the DLC pack mentioned in the Road Map. However, these are a bit more difficult in that you have to collect every weapon in the game. There ARE missable weapons, namely because of story progression when shops upgrade their stock, getting rid of weaker weapons. This occurs for both Abazet and Cota Mare. Be sure to purchase every weapon available at a shop ASAP when you come to it, and check upon every new arrival in a city.
If you need to raise money for a group of purchases at a shop, grind away on enemies and complete quests. There is also accessories with "Sacrifice" in the name that will increase SID gain, as well as Kamonds called Golden Clover.
All the weapon locations can be found in chronological order in this thread.
To unlock the achievements, you have to have all the weapons in your inventory, so DO NOT SELL ANY WEAPON, EVER! The only exception to this is the "Wooden Sword" which is Juto's starting weapon. This is removed from your inventory once he grows a pair and starts using real blades. Losing this item does not affect the achievement in any way. From then on though, you need to keep everything.