Alright These is how i made these mode. Follow the instructions carefully
Requirements & Steps
Mod Engine (Mainly for installing the mods): Install from these link https://www.nexusmods.com/sekiro/mods/6 Download it, extract the files in Sekiro's Directory where Sekiro.exe is located and then make a new folder named 'mods' Or watch any youtube video.
UXM (For Unpack the sekiro's files): https://www.nexusmods.com/sekiro/mods/26 bit complex so i recommend watching a tutorial video on Youtube. And i belive there will be a folder called sfx and in the sfx there will be one file called sfxbnd_commoneffects.ffxbnd.dcx.
WitchyBND (To Unpack files that end with these extension (.dcx) file format): https://www.nexusmods.com/eldenring/mods/3862 just extract it. And there will be WitchyBND.exe, these is where you drag the .dcx file to unpack it, example just drag and drop the sfxbnd_commoneffects.ffxbnd.dcx on the WitchyBND.exe and you will finds one folder called sfxbnd_commoneffects-ffxbnd-dcx-wffxbnd, now in the folder there will be another folder called effects and there is a lot of files in there that end with fxr, dont focus on any of them. just remember these
FXR Playground: Just go to the online website, just search fxr playground. Now upload any of the fxr files from the above, now i choose f000440448 which is ashina cross and upload it in the fxr playground, now there will be several tabs once you upload it. Focus on these two, Color and Scale. Color changes the well the color, dont play with any of the other options in the color tab just change the color to your desired color, for me i choose #26619C which is the color of Lapis Lazuli blue and my mod color, and after you have the color you want press recolorto save the color. Now as for the scale put it between 1.2 to 1.4 or 1.6 (If you want it a bit too long) and then press scale, dont recommend to put the scale above 2 otherwise it will mess up your game (How do i know... experience) and press scale to change the hitbox. Now at the bottom left of the website, there will be a tab called FXR files, there will be a small button called save, press it and then next to it there will be a download button. Press it and save it. You will download the file. Go back to the sfxbnd_commoneffects-ffxbnd-dcx-wffxbnd folder and effects and put the new file there, replace it and then repack sfxbnd_commoneffects-ffxbnd-dcx-wffxbnd by just dragging and dropping sfxbnd_commoneffects-ffxbnd-dcx-wffxbnd on WitchyBND.exe. and you will have sfxbnd_commoneffects.ffxbnd.dcx.
Installation: Now go back to your Sekiro folder and in the mods folder you should have created from step one. and make a sfx folder, in there put the sfxbnd_commoneffects.ffxbnd.dcx file.
Done!!!!
BTW in Fxr playground, you can batch select and upload several fxr files at once.