You can always run away by giving him a worthy song title.
There are two ways of getting to Arnold. One path has a slight detour.
Look at the boulder there. It can help crush Arnold.
For leverage, you have two items. One came from Algiers, and the other could have been used to kill Anton.
The ship rib or stalactite will do the trick. (See the last question to find out how to get the stalactite.)