The Mechitarist monastery on San Lazzaro is viewable by guided tour. This is a bit taxing on a very hot day with a very large group, but worth it. It contains a miscellaneous collection of art and objects, of which, aside from the religious artefacts, the most important are the collection of 4,000 Armenian manuscripts, stored and displayed now in a new rotunda room.
There are also Armenian gospel manuscripts, among many others, in a fantastic exhibition currently on at the British Library. 'Sacred' (not a record by Madonna) is an extensive comparative display of beautiful and curious religious texts and other artefacts of Judaism, Christianity and Islam. The diplomacy required to bring this off at this time is hard to imagine, likewise the cost: a considerable amount of material is loaned, there are art commissions, plenty of IT, and a high level of design and a a free gallery guide, and yet there is no charge for entrance. Great website too, with 'turning the pages' access for 16 items.