It's not too far away from the district you start in and can be seen from the symbol of the two theatre in arno's house/theatre you receive money every 20 mins so just keep collecting from the chest.
39+ Assassin's Creed Unity Does Arno Have Two Hidden Blades
PNG. Sword, dagger, throwing knifes, hidden blade, fists. Arno's hidden blade assassinations are literally the most badass ones ever.
Kewbuk Rs2bhm from styles.redditmedia.com
There is no option to fight with hidden blades or bare fists in unity. You just have one weapon instead of choosing between hidden blades, sword and dagger. Unity, arno dorian could alter his outfit in order to suit his needs.
Here's a video of the combat even though.
I've read that arno won't have dual hidden blades, and i kinda like that they're changing it up, because i always like my assassins creeds to be varied and updated, but i'm just curious how you will be able to do dual stealth assassinations. Reach the required level in assassin's creed initiates in the companion app, then find the find three keys after killing iron mask faction enemies, then unlock the door and collect the hidden louis xiv's note. Arno's hidden blade assassinations are literally the most badass ones ever. Obtained through collecting all the artifacts in the helix rifts.