... so does it have any legal protection?
IANAL, but from my investigations some years ago for my own interests.....
There are 3 basic levels of trademark usage:
1. A Trademark has legal standing simply by it being used
as a trademark. No formal intellectual property steps are required.
2. Adding ™ to it's use is an explicit statement of the claim of it being a trademark. Again, this can be simply added to each use of the trademark at the whim of the owner pf the trademark.
3. Registering the trademark allows the owner to use the ® symbol. The process allows for the trademark to be examined for uniqueness as well as being advertised for other parties to challenge. Once registered, it provides a firm reference which can be searched by anyone - as well as being formally available for the examination of any new trademark applications.
One of the most important aspects of registration is to establish a date after which there can be no argument that the trademark has an owner - otherwise if a situation arises where the date from which the trademark was used is needed to be known, proof will be required. This proof could be anything from a newspaper ad or other dated material to a business registration that uses the trademark in the documentation (this is especially relevant for text based trademarks).
In short, the "Dave hand" as it stands has protection. Registering it just makes defending it easier.