Guide to the location of Coat of Arms, solid number is the arena itself, the half numbers are in the transition periods. No spoiler tabs, so you can see without scrolling over.
Locations
Voke
Lamb -3 – Right after you enter the 3rd arena turn right. It’s behind the exploding crystal in that room
Goat -4 – Above the pit of lava in 4th arena. Easily visible when you first enter
Beast -2.5 – After leaving the 2nd arena and entering the crypts, go to the back right corner. The CoA is underneath the ceiling in the middle of the room
Archdevil -0.5 – Above where the first enemy spawns
Stygia
Lamb -4 – In the 4th arena, just before the exit, on left of it
Goat -3.5 – After you leave the 3rd arena, it will be far right of the main path to the next one. You can find it on some floating containers
Beast -1.5 – Right above the exit of the first arena
Archdevil -2 – After reaching the 2nd arena hug the cliff. In the very corner of the arena, the CoA will be hidden below the edge of the floor
Yhelm
Lamb -4 – In the 4th arena, under the bridge in its center
Goat -3.5 – At the top of the large staircase after the 3rd arena. It will be hovering in the center
of the empty space the staircase circles around
Beast -3 – It’s in the corner of 3rd arena, underneath the ceiling. Go opposite wall of the exit, and from the top of the staircase look slightly left (and up)
Archdevil -1 – In the 1st arena, on the outside of the wall on the right of the entrance
Incaustis
Lamb -3 – After dropping into the 3rd arena hug the right wall. The CoA is in a small alcove
right before the lava pool on the edge of the room
Goat -4.5 – Right before the bossfight, instead of turning right towards the staircase to the boss arena, turn left. The CoA is on top of some rubble in a side cavern.
Beast -1.5 – Beyond the first wave of enemies after the first arena, do a sharp right turn after passing a stone gate. CoA is on a small ledge above the lava moat
Archdevil -3.5 – Right before the 4th arena, behind the last rock pillar on the left, high up
Gehenna
Lamb -3.5 – After leaving the 3rd arena take the right path across the bridge. CoA will be near the edge before you go through the door at the end
Goat -2.5 – In the first room after leaving the 2nd arena (one with a staircase and enemies), it will be above the entrance door
Beast -4.5 – After leaving the underground of 4th arena, the CoA will be up high behind the first arch
Archdevil – 1.5 After the 1st arena and before the seraph spawn, it’ll be down the cliff on the left
Nihil
Lamb -2.5 – Just after the void stalker spawn after the 2nd arena. Go forward until the edge, then drop down and turn around
Goat – 3.5 – Right after exiting the 3rd arena, it’ll be up high between two pillars
Beast – 4.5 – Above the exit of the 4th arena (on the outside)
Archdevil – 1.5 – After the 1st arena, but before you fall down the hole. Look up high in the back of the ruins
Acheron
Lamb – 3.5 – Before the 4th arena, after you first drop into the area filled with containers. It’ll be on the left of the entrance, on containers, not ground level
Goat – 2.5 – Shortly after the 2nd arena, on the left side near the ceiling
Beast – 3 – Back left corner of the 3rd arena, up high
Archdevil – 1.5 – Turn left after the 1st arena, and right before the path turns right turn around instead. One of the containers has their back open, and inside is the CoA
Sheol
Lamb -0.5 – After reaching the bridge at the very start of the game turn around and it will be in the mouth of a statue
Goat – 1.5 – In the middle of all the ‘arches’ right after the first arena (in the air)
Beast – 2.5 – Right before entering the third arena, look up
Archdevil – 3.5 – Right before entering the fourth arena, turn around and look down the cliff. There is a hidden alcove with the CoA peeking out