On balance, economic sanctions are reducing the threat russia poses to western interests?

This is a highly debatable question: we don't have a definite answer, and if we did the politicians and the economists would not be debating it.

I think this is rather not the case. The economic sanctions are not meant to reduce the threat to western interests. Rather, they are meant to demand specific decisions, such as withdrawal from Crimea. They are aimed at specific problems, rather than at weakening Russia generally.