When countering enemies with the axe or spear, Ezio will lose the weapon as it will be impaled or buried in the target.
You can easily reclaim the weapon by picking up the corpse and dropping it. The weapon embedded in the dead body will pop back out for re-use.
Easter Egg: Super Mario Bros. Reference
At the beginning Sequence 3, the character Mario exclaims "Itsa me, Mario!" A clear reference to the 52nd Governor of New York, Mario Cuomo. Or Super Mario. Your call!
Unlockable: Abilities
The following items can be unlocked by performing the actions below:
Climb Leap Ability - Complete Rosa's mission "Monkey See, Monkey Do" in Sequence 7 to earn the climb leap ability. With this ability, you can make longer jumps while climbing, letting you grab hand holds that'd normally be out of reach.
Disarm Combat Technique - Complete Mario's "Evasive Maneuvers" mission in Sequence 5 to unlock the disarm technique. Disarms let you counter incoming attacks from weapons that are normally too heavy to counter (like axes).
Easter Egg: From the Deep
In Santa Maria Delle Visitazione, in the Assassin's Tomb, you'll come across a large flooded room just before one of the Armor of Altair seals. Pull the lever and peer into the water. Wait a minute or so and you'll see a shadow below. Pull the lever again and peer into the murky depths once more and a tentacle will reach out to grab (and miss) Ezio.
Hint: Lower Your Notoriety
If you're close to getting a "Notorious" rating, go to a Herald and bribe him. After you bribe him just steal the money back.
Unlockable: Equipment
The following items can be unlocked by performing the actions below:
Condottiero War Hammer - Collect 50 hidden feathers and the Condottiero War Hammer will become available in the blacksmith's shop in the Villa Monteriggioni.
Auditore Cape - Collect 100 hidden feathers and then talk to Mario in the Villa Monteriggioni. He'll award you the Auditore Cape.
Hint: Free Medicines and Throwing Knives
If you've got room in your inventory for more medicines or throwing knives, loot dead bodies and you'll occasionally find these items for free.