Complex sentence: Still, martinets were still sold in the pet section of French supermarkets; it is generally believed that a large share of those sold are meant for use on children, not pets, or at least to threaten them.
Split into simpler sentences: Still, martinets were still sold in the pet section of French supermarkets. Many believe that a large share of those sold are meant for use on children, not pets, or at least to threaten them.