The ranking you speak of is PEACe inex, not safety index... That would mean nothing just because France is involved in several peace enforcing operations round the world, and need some military equipement to do so. Just for that, that will make the country have a low rating considering the criterias this index is based on. But that doesn't mean the country isn't safe.
Also, not to mention that this index is a PERCEPTION index.....
Let's just take an European example... France isn't less safe than Netherlands, but netherlands dont get military operations ongoing all around the world, and that makes a difference for this index. Same for Belgium, Germany, and so on, all in top 20 of this rating