You get this after you collect all Viewpoints, Chest, and Cockades in Versailles.
It is entirely possible to get this before you even finish the first Sequence, but is obviously easier later in the game when you have upgraded weapons and equipment.
*** Spoiler - click to reveal ***You don't have your assassin's blade yet, so you can't stealth kill any guards and have to fight them (there are a few chests that are guarded), all while using the weakest weapon in the game. Well, you can knock them out, but that takes a bit of time and can be interrupted.
You are able to return at any time after Sequence 3, so if you don't get it all right away, just look for the V icon on the Paris map and you can return to Versailles. I personally waited until I had actually beaten the story before really focusing on this, and so it was really easy to get everything.
The 2 Viewpoints are both marked on your map from the start, and after synchronizing those with
, you should be able to see all the chests (and a few cockades) on the map. Edit: These may not actually be required to get this trophy (but I'm not going to put the leg work into finding out
).
There are 20 Chests, 9 in the Saint-Louis district (eastern), and 11 in the Recollets district (western). These chests are all unlocked chests (gray), so they do not require any lock picks. You do not have to get the Yellow or Blue chests to get this trophy. Unless I am mistaken, all chest locations are shown on the map after you sync the viewpoints. To open the chests, just use the
button when standing in front of the chest (make sure the camera and Arno are both looking towards the chest or it won't give you the option).
The 8 Cockades (4 in each district) are actually the most difficult set to get as they will only be marked on your map once you get close enough to them. Most of them are near chest locations, so those will show as you get the chests, but there are a few (two for me) that are not on a chest path, and will require searching or using one of the strategies below. To collect these, you will need to cross through them in some manner (either just walking through or jumping through).
The easiest way to find all of these is to purchase the
Cockades and Chest Map from the
Time Saver Packs in the
EStore as it will mark every location of all cockades and chests in both Versailles and Paris - this also helps you get:
This does require 150 Helix Credits, though, so unless you have extra (which I ended up with 500+ by the end of the story missions and had nothing else to spend them on), I wouldn't worry about it.
Alternatively, I would suggest you just use the YouTube video (not mine) below that will show you where all the cockades are.
Edit: Just saw this link over in the trueachievements solution to a PS4 YouTube video (yes I see the irony in that statement) that has all the chests and cockades on it, which you can use if you are missing any chests - it's the second video.
Warning, it is extremely slow as there are no edits/cuts - you get to see them run/climb from one collectible to another. So unless you are really stuck, I'd suggest using the first video.