Have you seen or used a foost knife (pictured above and below), KiddiKutter or the Kiddies Food Kutter? These are all knives designed for children. They are serrated but blunt. Meaning a child could use them without the risk of cutting themselves.
The foost knife Otis is pictured using is so blunt it would be impossible for him to cut himself. These knives rely on the children using, especially on hard vegetables, an exaggerated sawing action to cut the food. Otis (5 years) is free to choose which knife he uses and will only use the foost on soft foods. For hard foods like apple, carrots, potato or pumpkin he prefers a sharper knife (he most often uses a sharp serrated paring knife). The best thing about the foost is that it is really small, the handle is the perfect size for his hands. It is molded and fits better than any other knife he has used.
I would recommend the foost (first knife and next knife), and Kiddie Kutter type knives for children who are young (toddlers) and/or are completely new to using a knife. I would recommend it for cutting soft food only. When children are ready to cut harder foods it is time to move onto a sharper knife. It doesn't benefit a child to have them cut hard food with a blunt, albeit serrated, knife.
In Montessori, we provide real, child-sized, materials. Many families would benefit from using these children's knives, but only in the short term. Children don't need blunt knives. They need to be introduced to knives in a way that is safe and suitable for their skill level. We need to increase the risk the child is exposed to with the level of responsibility they are ready for. For every child this will be different.
One of the benefits of these chlidren's knives is that the companies often do good work towards promoting healthy eating including children being involved in preparing and eating vegetables. And for many families these knives can be a great way of introducing children to using a knife.
You might also like to read my related article - Where is the risk? Why children should use knives (and other dangerous things).
For those that are interested, the knives my children use the most are the Victorinox Serrated Paring Knife and the Kuhn Rikon Serrated Paring Knife. These knives are sharp and need to be introduced to children gradually and under strict supervision.