But the problem is, why did they appear in my ledger?
I never did this operations. Is my BTC's in my wallet in danger?
From the timestamp and ledger order it looks like you ultimately received these coins (deposited then withdrawn from an online service? or refunded a purchase maybe?).
If you are indeed using a watching-only wallet with an offline signer, then I do not expect your coins to be in danger. As I said, weird ledger behavior and particularly transactions disappearing is symptomatic of database corruption. However, transactions appearing out of nowhere usually isn't.
If you really can't remember how these coins got to move, maybe you'd like to open a ticket and provide us with more details as to how you came across this issue to begin with:
https://support.bitcoinarmory.com/homeYou currently haven't provided enough information to conclude anything. However, we never had a case of stolen coins with offline wallets, and as you can see, those coins came back to you, so I don't think there is too much cause for worry.
If you would regardless prefer to stay on safe side, you can create a new wallet on your offline signer (or a different one if you are really paranoid) and move your coins to that in the mean time