When you unlock an item in For Honor through an in-game action or by redeeming a key (for example, a ULC or Season Pass), you will be notified by a message in-game that new items were unlocked.
The location of the unlocked item depends on the type of item. You can find them either in the Customize or Social tab, accessible from the main menu.
In CUSTOMIZE you can find:
Effects, Executions, and Emotes
In SOCIAL you can find:
To change your hero's gear, outfit or ornaments navigate to Customize, select Heroes.
Select the Hero you want to customize (you can only customize a hero that you have already recruited) and select Customize again on the next screen.
On the following screen, you can select the piece of gear you would like to change (Helm, Chest, Weapon, Arms).
Navigate left or right to change Appearance or Abilities. A small yellow icon with an exclamation mark inside will show you that you have a new item.
Navigate to Appearance on the left. You can find your unlocked Outfits, Ornaments, and Patterns and equip them here.
Navigate to Abilities on the right. You can find all Effects, Executions, and Emotes you unlocked and equip them here.
EFFECTS, EXECUTIONS, EMOTES:
To find your unlocked Scavenger Crates or to buy new Scavenger Crates, navigate from the main menu to Customize, select Heroes, select the hero you want to receive the items from your scavenger crate (the items do not transfer between heroes, they will be placed into the inventory of the hero you select here) and select Scavenge Gear on the next screen.
On the top, you'll be shown an overview of the number of crates you currently own.
In the middle of the screen, you can find a breakdown of the types of crates. If one of them has a small crate symbol next to it, you currently have a crate of that type.
If you are shown a price in Steel, you do not currently own a crate of that type but can purchase one here.
On the right, you will find some information about the content of the crate. Yellow circles mean that you will receive a corresponding number of higher quality gear items.
To find the Emblems, Emblem Outlines, or Champion Status you unlocked, navigate from the main menu to the Social tab.
To find new content for Emblems, open the Emblem Editor. New items will be marked with the small yellow exclamation mark to help you identify them. You can use them to change your emblem here.
If you unlocked Champion Status, you can activate it from the Social tab by clicking on the Champion Status tile. On the following screen, you can either activate the Champion Status you unlocked or buy more for Steel.
Champion Status is stackable - you can activate more than one pack. The screen will show you exactly how much time is left on your active Champion Status.
Here is the TL;DR version of where to find your unlocked items:
Gear (Armor or Weapons): Main menu > Customize > Heroes > [select a hero] > [select the type of gear you are looking for]
Outfits: Main menu > Customize > Heroes > [select a hero] > Appearance > Outfits
Ornaments: Main menu > Customize > Heroes > [select a hero] > Appearance > Ornaments
Effects, executions, and emotes: Main menu > Customize > Heroes > [select a hero] > Abilities > Executions/Emotes/Effects
Scavenger crates: Main menu > Customize > Heroes > [select a hero] > Scavenge Gear
Champion Status: Main menu > Social > Champion Status
Emblems: Main menu > Social > Emblem Editor
Emblem outlines: Main menu > Social > Emblem Editor
If you have difficulties locating items that you unlocked, please check if they were activated, downloaded and installed correctly.