I've placed two daggers into the same display case and I cant pick them up. ???? It says I need a dagger equipped to place it on this rack. But there are 2 already there. One I'd covering the other.

i had the same problem, i placed one dagger in, then a short while later when i tried pick it up it simply placed my current dagger inside, the first dagger became unable to interact with

In Hjerim, yes? Don't activate the cases. They are bugged. Instead, open the lid and drop your dagger in. I hope it wasn't something valuable because it is gone forever.

at least the dagger my got stuck was a iron, i've put it there for the looks.

Lol I havent even bothered to put any daggers I have away even though I have like 20 daggers made by me. Thanks for the warning!

The thieves guild have rigged them.

They both were valuable daedric blades... Yes it was in the house in wildhelm.