Info required on new found German / Luftwaffe relics

[Jon]

Hello to you all and a Merry Christmas.

I have just been given a box of relics by a British soldier, all are items he "Liberated" from when he landed just after D Day upto entering Germany at the end of the war. Some i am sad to say are the usual bits of uniform, insignia cut from dead enemy soldiers as momentos including a very nice camera he found on a dead officer, also a great condition Luftwaffe Officer dagger with it.
One arm band has the letters RLB over a small swastika, the arm band is dark blue with silver brading along the top and bottom. I have looked on the internet and can find it belonged to the " Air Defence " ?? but can find no details as to what they did.

Would the owner have been with Flack units, Home guard , ARP ?????