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This question is not as simple to answer as it may seem. A friction lock baton is not classified as a weapon (meaning it doesn't require a special license), as per Federal Law # 3 of 2009, which defines weapons as:
a ‘weapon’ as: Including a firearm, air gun, sound gun, flare gun, hunting gun, antique gun and stun guns; and
a ‘firearm’ as: A weapon that launches a projectile by the pressure resulting from the combustion of the propellant material. This definition excludes the air gun, sound gun and photo gun. However, it states any firearm parts, components or spare parts shall be considered firearms.
In practice, replica weapons also need special permits to be imported.
This means that you don't need a permit to import it into the UAE. However, a baton is considered a weapon as far as the airline and transport industry is concerned, and is listed in the list of things prohibited in carry-on luggage by the UAE airport regulator:
All types of hammers
All types of nails
All types of screwdrivers and sharp work tools
All types of scissors with blades longer than 6cm
Personal grooming kit (parts longer than 6cm will be confiscated)
All types of swords and sharp objects
Handcuffs
All types of laser guns
All types of replica firearms
All types of firearms, ammunition and flare guns
All types of lighters (only one lighter is permitted)
All types of bats
All types of martial art weapons
Drills
All types of ropes
All types of measuring tapes
Packing tape
Electrical cables except for personal use
Walkie-talkie
You can find a similar list for example, at etihad airways website.
So, in short:
If you walk around brandishing it, you will most likely get stopped by police as it is illegal to carry weapons in public.