Perhaps the most interesting thing that can be said about Arisaig is that, in the right light, it is incredibly beautiful. The second most interesting thing is that it is the base for the ferry to Eigg.
Thirdly, a chap by the name of John Silver was born in Arisaig on 2 January 1853 who, as a young man, went to work on the construction of the lighthouse at Barrahead.
This was designed by Thomas Stevenson, father of Robert Louis Stevenson.
It is claimed that R L Stevenson met Silver on a few occasions and it seems possible that he took Silver's name for the character in Treasure Island. However, Stevenson is clear that the actual character is based his real-life friend William Henley, a writer and editor so only the name derives from this son of Arisaig.
There may be less interesting facts about Arisaig, but I'm afraid you will have to research them yourself.