The musueum has a well-organized webpage which gives the following information (here) of their collection of Byzantine Art, including manuscripts:
The Byzantine collection links the ancient Greek world to that of modern Greece. The collection is exceptionally rich, although it is not representative of all the different artistic tendencies and currents which flourished during the thousand-year Byzantine Empire, and is divided into two groups.
The first group comprises bronze and silver household and ecclesiastical vessels, miniature sculptures and enamels, ceramics, manuscripts, etc., many of outstanding quality and workmanship.
The second group includes Byzantine and post-Byzantine icons, through which the evolution and development of iconography from the Byzantine period and the Palaeologan renaissance can be traced in the workshops of Crete and the artistic production of Mount Athos, up to the early stages of the modern Greek painterly tradition.
A number of household vessels from the early Byzantine period (4th to 7th centuries AD) help to create a picture of the domestic surroundings of late antiquity. The rich selection of lamps and chandeliers is also of especial interest.
The important collection of decorative silver plates dating from the late 6th and early 7th century clearly preserves the subject matter of the artistic tradition of Greco-Roman antiquity and the manner of depicting the human figure. The Museum's collection of ceramic platters likewise offers a rich selection of decorative themes.
Several ecclesiastical vessels, censers and chalices, dating to the early Byzantine period, as well as other groups of objects such as matrices, tools and measuring instruments, cast light on contemporaneous trade, crafts and scientific advances.
The entrancing collection of Byzantine jewellery presents an obvious continuation of Roman forms and techniques, including golden necklaces and earrings set with sapphires, amethysts, emeralds and pearls, and exquisitely worked bracelets and rings decorated with Christian emblems.
A large group of crosses, reliquaries, amulets and miniature steatite icons are indicative of the rich production of small-scale works of art in Byzantium.
A number of superb censers and processional crosses are representative of ecclesiastical vessels and furnishings of the middle and late Byzantine periods.
Finally, it is worth noting that the general public has always reserved its greatest affection for the Benaki Museum's collection of Byzantine and post-Byzantine icons.