Arm of Beowulf locks out 2-handed Longswords?

[Zaibatsu]

I'm unclear regarding the Arm of Beowulf perk. I understand it allows the option to hold a longsword along with Shield and torch. But without those, would it count as holding a single weapon? As such would it proc all the single-weapon perks whilst having an empty hand?

Additionally, does it lock me out of holding longswords with 2 hands? The perks has some drawbacks, but I can't seem to find a way to hold longsword back with 2 hands now.

Please share some insights if anyone has any, thank you.

[Das Trojanische Pferd]

as long as you have nothing else in your other hand you use it with 2 hands