I've looked in ultimate items but I can't really find any specific items that I can yern for in my campaign I'm in. Any suggestions
Just alter the descriptions of existing items to give them the feel you want. There are a bunch of 3PP that cater to your interests. Just make sure your GM is cool with it.
But wouldn't that change the mechanics of an item if i wanted a special Magical Weapon but i wanted it as a Katana? So my Weapon Focus and Weapon specialization works on it. At that point wouldn't I not be able to change it.
I have a product coming out soon that might meet some of your needs. Call to Arms: The Daisho from Fat Goblin games doesn't cover a ton of asian wondrous items, but instead goes over multiple types of samurai weapons (magical, mundane and specific named weapons). It also includes magical scabbards, new weapon properties and other options for asian weapons.
For clarity, the nihontō in The Daisho are written as distinctive and different blades from one another, not just in name but also in mechanics. This isn’t completely historically accurate, but for the simplicity of the game. Examples of weapons included are: Chokutō, Kaiken, Katana, Kogatana, Ōkatana, Nagamaki, Tachi, Kodachi, Ōdachi, Nodachi, Tsurugi, Tantō, Kabutowari, Yoroidōshi, Uchigatana, Kouchigatana, Ōuchigatana, Wakizashi, Kowakizashi, Ōwakizashi, and the Zanbatō.
You can also search on PFSRD like for example for Katana or o yoroi or samurai or tian and then filter for magic item.
Examples of weapons included are: Chokutō, Kaiken, Katana, Kogatana, Ōkatana, Nagamaki, Tachi, Kodachi, Ōdachi, Nodachi, Tsurugi, Tantō, Kabutowari, Yoroidōshi, Uchigatana, Kouchigatana, Ōuchigatana, Wakizashi, Kowakizashi, Ōwakizashi, and the Zanbatō.
Wow! That would be some detail that you are going through. Some of those are broad categories of swords, some are different lengths of a type of sword, some are just distinguished by time periods, and some are different swords altogether that usually get lumped together in one or two names of Japanese swords. I am impressed that you will list all of those out separately and interested to see what game mechanics might distinguish them.
Good luck and keep us informed for the publication!
As for a katana of X it says in the magic item creation rules that if you want a special weapon but want to change the base weapon you simply subtract the cost of the base weapon and add the cost of the new weapon so that you make a luck katana or whatever
I may be parsing this differently, but I think what is being requested is not simply analogs of existing items with an Asian Polish, but for specifically themed items of a magical nature that are contextually culturally apt.
Some things, like incense and pearls of power and other things of a miscellaneous nature are certainly appropriate, but going outside of that box gets trickier when one is not completely versed in the cultural more sand particular nuances that give the feel of what one wants to convey.
I am by no means an expert, so making the comparison of the spoon that produces what is described as porridge with the taste and consistency of wet cardboard might be refluffed as a bowl and mallet that can multiply a unit of rice into enough to feed a group, by pounding it into multiplied mochi cakes. If you're running a game where there will be lots of spirits and outsiders, you would be remiss in leaving out ofuda or shimeware if you are planning to include some variation on Shinto. Origami charms are a given, and cultural miscellany abounds from daruma to figurines of power that aren't necessarily combat-related.
Of course, this is assuming that you are focusing in a more Japanese direction. You could end up pulling from Thai lore, Korean, the wealth of Chinese history, take it in a more Vietnamese direction...
I'd really advise hitting up the Dragon Empires books/content, since a lot of the inspiration-drawing has been done for you. And then looking at the materials and cultures from which they were sourced, because there's a ton more to mine.
But that's assuming that such is what you're after, the way I sorta looked for things more akin to how Nyambé handled African-themed materials, items, and props for that style of adventure.
I'd honestly go HERO on this. What do you want the X to do? Are you wanting to pull from Y legend? If so, what does the X in that legend do? Is there a current gizmo that does that thing? Great! Reskin it. No? Then take the X from Y and build it.
The tough thing is if you have no real knowledge of Japanese / Chinese / Thai / Korean / Viet / etc. legends. If you have no knowledge of the English, French, and Christianity, then the Knights of the Round Table and the Quest of the Grail is going to make no sense to you; you see a couple or three artifacts in there, a bunch of named magic items (The Green Knight's Belt, Lancelot's sword Joyeux), and you go with that - but because of a lack of reference, you might not understand why they're important, or what they should be able to do.
Reskinning - it's your friend.