Yes, sadly this is largely another misattribution. The
dolphin handle design was used for lots of things, including helmets.
There are a few known example of helmets with a
dolphin handle. See the illustrations below.
However, there are many more examples of this
type of
handle attached to drawer or chest parts.
The difference is in the way they worked. Drawer and chest handles only
had to lift a slight amount away from the surface, so they could be thick and wide. But helmet handles
had to lift a full 90 degrees away from the helmet surface and rotate back and forth. So all known helmet handles are very thin, otherwise the wide parts prevent the required functioning.
Take a look at the difference between yours and the two below. The
dolphin handles for helmets are really just thin handles with a
dolphin design - total different from the common flat and wide
dolphin handle.
I have three
dolphin handles all of which are also wider than the helmets ones. Likewise none of the ones shown in A&L are from helmets. It appears that a very very small number of
dolphin handles were used on helmets.
The vast majority of known helmet handles are the thin
type seen below with nice spine or knob ends. Though almost identical ones were used on drawers and chests as well so even they are no guarantee of being a helmet
handle.
SC