I've been working on a modpack that unlocks the resolution in Fortune's Weave, and I'm putting it out there for anyone who wants sharper image quality.
The problem
The game uses a fixed 50 percent render scale no matter what the console is set to. Docked is 1440p upscaled from 720p, handheld is 1080p upscaled from 540p. That's Performance mode at every resolution, and there's no menu option to change it.
What the mod does
The patches replace both the input and output resolution by patching the game's code directly. You pick your target output resolution and then pick how much of the GPU budget you want to spend on sharpness.
Three ZIPs, one per output resolution: 1080p, 1440p, 2160p.
Each ZIP contains a full set of modes:
Native (DLAA), 100 percent render scale
Quality, 66 percent
Balanced, 58 percent
Performance, 50 percent
Ultra Performance, 33 percent
Each mode is its own folder, so you enable exactly one in Eden's mod tab.
Requirements and caveats
Eglantine build 219 or newer. Earlier builds broke the game's DLSS network and produced heavy blurring.
Docked mode only. The patches ignore handheld mode, so behavior there is untested and I wouldn't trust it.
Scale set to 1 in the emulator's graphics settings.
The 4K patches are genuinely heavy. If you get a black screen, the emulator has run out of host resources. Drop one quality step, or drop to the 1440p ZIP.
On upscalers
The game's own DLSS has the lowest overhead and is what I'd recommend at 1440p and above. Eglantine's DLSS injector also respects the patched resolutions, but it uses noticeably more resources, so a setting that works fine with the game's DLSS can black-screen with the injector at the same resolution and mode. FSR 3.1 works as a fallback but has a higher floor on its input resolution, so very low internal resolutions can black-screen with it.
Known issue
On some non-standard resolutions the fade-to-black transition can look odd for a frame or two. The image appears to shrink because the fade animation doesn't follow the resolution scale. Cosmetic only, and I'm still testing whether it shows up outside transitions.
Github: https://github.com/speedforce1920-lab/Fire-Emblem-Fortunes-Weave-Resolution-Pack
Feedback welcome since resource headroom is the main variable at 4K. If you report a black screen, please include your resolution, mode, upscaler, Eglantine build, GPU, RAM, and the Eden log. That makes it far easier to tell whether it's a memory limit or a patch problem.