Goal of this guide is to get smooth 1080p experience with a proper UI scaling, AA and adaptive sharpness (which looks very nice on textures).
All in vanilla version and without any gameplay modifications.

Before you begin
1. Always be careful when using any mods or tools, it's better to limit network activity if possible or at least scan it with av!
2. Always backup your saves and original game directory.

"Native" 1080p
By luck I have stumble upon PureHD project which looks like the only tool that provides decent UI scaling rather than simple stretching.
There is not much info about it, other than mention on PCGamingWiki which is kinda strange.

1. Download/Install PureHD (https://www.pcgamingwiki.com/wiki/Sacred#High-resolution_rendering)
Copy pureHD.exe and pHD.dll to the root game directory.

2. Configuration
Add/Change these lines in Settings.cfg:

PHD_RES_SCX : 1920
PHD_RES_SCY : 1080
WAITRETRACE : 0
COMPAT_VIDEO : 1
DETAILLEVEL : 2
FONTAA : 1
FONTFILTER : 1
FSAA_FILTER : 0
FULLSCREEN : 1
GFX32 : 1
GFX_LIMIT128 : 0

3. Check that pureHD.exe runs properly.

D3D12 translation
Sacred is originally using DX7, let's translate it to 12.
Game will behave much better under Win10+ (i.e Alt+Tab and OSDs will work properly), also it's required to get ReShade working.

1. Download/Install latest stable version of dgVoodoo (http://dege.freeweb.hu/dgVoodoo2/dgVoodoo2/)
Copy dgVoodooCpl.exe, dgVoodoo.conf and everything from MS\x86\ to the root game directory.

2. Configuration (dgVoodooCpl.exe):
x Select [General] Output API: Direct3D 12
x Check [DirectX] Filtering: Force Antisotropic 16X
x Check [DirectX] Filtering: Force filter only if not point sampled

3. Check that pureHD.exe runs properly with dgVoodoo.

SMAA + FidelityFX Contrast Adaptive Sharpening (CAS)
Finally let's get decent antialiasing with adaptive sharpening using ReShade.

1. Download/Install ReShade (https://reshade.me)
x Select pureHD.exe
x Select Direct3D 10/11/12 API
x Select Standard and SweetFX packages

2. Configuration
-> Run Game
-> Hit Home key
-> Enable CAS.fx and SMAA.fx processors

3. (Optional) create shortcut for pureHD.exe for convenience.

Notes
- Despite all the daisy chaining, game runs relatively stable, there is no blocker issues or heavy glitches.
- Never forget to save your progress constantly, F8/F9 is your best friends (yes in Sacred you can fail your quests permanently :) ).
- Rarely game fails to properly draw itself on first launch, most likely due to some race condition.
Fix: Just re-launch it.
- I wonder if this Frankenstein will run under Linux with Proton/DXVK XD... are someone willing to test it?
- https://iryoku.com/smaa/
- https://gpuopen.com/fidelityfx-cas/

EDIT: Confused PureHD for Reborn, ignore previous comment.

Sacred NL is more customizable anyway.

Thanks a lot!!!

This is exactly what I was looking for. So many games have widescreen mods that also come with changes to the core game. It's irritating as hell.

All I wanted was widescreen support and this achieved that! Thanks again.