Different types of blades have been phased out, or relegated to purely ceremonial purposes at different types. As far as cutlass are concerned, they ceased to be issued except for ceremonial purposes in the Royal Navy in 1936 under Fleet Order 4572[1]. However, they were not all returned immediately with some ships carrying them for some time after the order was issued. The last time that a cutlass was carried into action by a sailor of the Royal Navy was in 1940 during the Altmark Incedent. There may also have been a cutlass carried into action by a sailor of the US Navy during the Korean war, by I have not been able to find a reliable source for this.

[1]: Swords for Sea Service by Cdr W E May and P G W Annis, volume 2, page 90