You don't need to download the blockchain to generate a wallet, you can always create the transaction on an online computer then transfer it using a usb the offline computer, sign and use online computer to broadcast it.
Bitcoin Armory can't sign normal raw TX. I don't know if there is any script which can do it. You can use CounterWallet to create a Armory compatible raw unsigned TX.
How about bitcoin core ? We need to download the blockchain or no?
Yes, you have to but you can also use Bitcoin core like ranochigo told. You might be interested in
https://bitcointalk.org/index.php?topic=958960.0 but I haven't verified the source code yet.
-MZ
My bad, mixed up armory with electrum somehow. Thanks for correcting. Bitcoin core can sign raw tx using the RPC console so blockchain isn't really required since you can still spend them by signing and broadcasting the transaction.