Sequence 7 - Clothes Make the Man
Your task is to steal guards clothes and boat. Run across rooftops to the nearest chest marked by Ugo. You can open it in two ways: distract the guards with the help of the thieves, who are standing in front of them  or sneak from the riverside. In the second case you won't have any problems and any costs. 
Second chest is located to the east. Your work will be a bit harder here.  Fortunately, you can use thieves - pay them and they will distract your enemies. 
Third chest is well guarded too.  However, you can gold from the roof -guards will start to collect it and then you can take all things. 
Finally, you'll have to get to a nearby boat. Try to avoid the guards, simply jump to the gondola and then quickly sail away.  Guards do not here bows here so they only can throw stones. Go to your friends and give them your boat. 
Sequence 7 - Cleaning House
Get back to Antonio, who will give you details of the next mission - the elimination of some traitors.  The nearest one is located in the north on a large ship. 
It is not particularly difficult to get rid of him - swim to the stern. Then climb on the boat in a place where there are no railings.  Wait for the enemy and murder him. 
Guards will be alarmed but it will be enough to jump into the water.  Of course you can also eliminate all enemies in all ships. In this case, start from smaller vessels. Second target is south-east from here - there should be no problem with him, he will attack you alone. 
The last traitor will be more cautious - he moves along with his soldiers. Fortunately, there is a simple way to kill him. Look for a place under which you will find hay.  ump to your hideout and turn to the fish market - use the vision and you should see your target.  Wait patiently - after a while, he will come up. Then do your job.
Sequence 7 - Everything Must Go
Return to Antonio and start your final mission. Talk with your friends.  The first task is to eliminate 5 archers that are guarding the villa. Begin your "party" from the north. 
First archer is on the roof. You can kill a second one by throwing him into the abyss. Now, move on to the south and kill another three objects.  Go and meet the rest of you comrades at the proper location. 
Now, you have to kill your target that is inside. You can get into the house in several ways, but I will recommend you to start from the eastern wall. First, kill the archer that is standing on the building on the other side of the river and then climb on the tower.  At some point turn north and climb further. 
On the roof eliminate four guards and then go down from the south. Jump on your target and walk away - leave other soldiers.  Now talk with thieves and end this sequence.