Every item in the game will be beneficial for your characters' abilities. They may, for example, increase your damage output, your survivability or your stealth skills. Some items may be bought from the beginning of the game, where the rest have to be unlocked by completing a specific mission or finding a schematic. Both of your heroes may use a different set of items although some items require having a specific level. Don't spend your money for items which you cannot use at the moment.
We have described the best available items and the ways of unlocking them.
There are three types of available melee weapons: Kukri (mostly the deadliest one), Cane-Sword (good for stunning your enemies) and Brass Knuckles (which is somewhere between the other two types). Basically the weapons are very similar to each other so just focus on the item stats since it will allow you to choose a weapon with the best damage output. However Kukris are the best if you prefer to fight in the open battles.
Master Assassin's Kukri - reach Loyalty level 5 with Henry Green.
Dove Cane Sword - complete every mission related to Queen Victoria's memories.
World's greatest cane sword - reach Loyalty level 5 with Robert Topping. Reach level 10 to unlock.
Eagle's Splendor Knuckles - conquer the Westminster district.
Basically every new item of this type is better than the previous one and will increase you attack power. Try to buy new gauntlets as soon as you can.
Legendary Assassin Gauntlet - Reach Loyalty Level 5 with Clara O'Dea.
Firearms are useful mostly during the open battles since they are too loud to allow you to kill you enemies and stay undetected at the same time. In most cases the expensive a gun the stronger it is. If you use firearms in battles often try to choose a revolver which has a short reload time and if you prefer to use only from time to time - focus on the highest possible damage.
The Mars - Reach Loyalty Level 5 with Ned Wynert.
Belts (Jacob) and Capes (Evie)
These two set of items have the same function and will increase your defense as well as the stealth mode. Nothing to overthink here - they have clear power increment.
Royal Cloak (Evie) - complete every mission related to Queen Victoria's memories.
Aegis Cloak (Evie) - find the unique crafting material from the locked chest in the Strand district.
Legendary Assassin Belt (Jacob) - complete every Sequence.
Beer Collector Belt (Jacob) - collect every available Beer Brand.
This item category provides a lot of different modifiers, mostly related to specific types of weapons. For example, if you have decided to use Élise outfit, be sure to use a kukri, since it will be only weapon affected by the available bonus.
The Aegis (Evie) - locate all of the Secrets of London and place the musical discs in Reuge's Vault.
Baron Jordane's Finery (Jacob) - find a schematic inside a Large Locked Chest on top of St. Paul's Cathedral.
Maximum Dracula (Jacob) - received after finishing the last memory in Sequence 8.