A book: This is the 20th Anniversary Slytherin House Edition of Harry Potter and the Philosopher's Stone.
A weapon: This is Lucius Malfoy with his walking stick. It concealed his wand and was used as a weapon by him during the Battle of the Department of Mysteries. It has been conjectured that the cane could be enchanted with a Shield Charm, which would be used defensively in a duel, in conjunction with the wand that was used for offense.
An item with a snake: This is the door to the Chamber of Secrets as seen in the Warner Bros. Studio Tour London. It was built by Salazar Slytherin and enchanted to open when commanded in Parseltongue.
An item with an emerald: This is the Slytherin House Hourglass, which is located in the Hogwarts Entrance Hall and used to record the number of house points that have been awarded or deducted with emeralds.
An item with a water element: This is Professor Slughorn’s Hourglass, which is a clock made of two connected glass vessels through which sand and a green fluid flows. It is used to measure how interesting a conversation is.