In all honesty, you don't need any of that to complete the game. It may make the battle longer, but you can manage just fine with average gear. I defeated the final boss in the low-mid 60s without any of the best equipment.

That said, many of the best weapons and armor come from the Bazaar. If you don't already have them, I highly recommend acquiring as many monographs as you can, as they are very beneficial for getting loot.

The Ultimate Equipment Guide lists the easiest way to get all the best gear. Note that you can still get the Zodiac Spear even if you opened some of the chests, it's just a very very very low drop rate, and you must have the Diamond Armlet equipped.

An easy way to level, in my opinion, would be to equip Embroidered Tippets while you're hunting for all those Bazaar goods for double exp. It does take a very long time to get some of those drops, especially the ones that require chaining rare game monsters.

~DragonHeart~