Here are all locations of reliquaries with screenshots below.
The very first one is
1-9
2-3) When entering house with rocky yard, check left and right rooms.
4) On a table inside this lovely pagoda.
5) Next to a bell.
6) in a garden central sitting area.
7) First house your enter – check left room
8) Under a path with 3 guards upstairs
9) Next to the last patrol inside
10-18
11) and literally above №10
12) After you run away from a helicopter
13) Next to a sniper riffle
14) Jump down below the sniper riffle area and walk back
15) Continue normally with the sniper, check left square
16) After escaping from a firing vehicle inside
17) After a very challenging fight with hogs
18) Before the log pathway
19-29
20) On a small platform
21) This one was glitching for me: sometimes it wouldn’t appear O_o
22) When you defeat two angry kittens and about to grapple, don’t!
Check behind the roof
23) Face this fence and walk backward (see in bottom right?)
24) In plain sight
25) Check this building
it’s there!
26) The area with many enemies, first central tower – left shelve
27) Check with distance mark, the relic is on a floating rock
28) And another one
29) By the final battle arena
but I need 50!
1) Go to the main menu, select play specific episode “Close Call”.
2) Any difficulty, keep all your abilities and progress.
3) Pick up those 3 relics, exit to main menu and… repeat 6 more times.
Success?!
Get Rich
Acquire 20 “Reliquaries”
&
Get Richer
Acquire 50 “Reliquaries”
Thanks to Lord Of War for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.