Holding all your money in one address = Paper wallet? A paper wallet is a very misnamed term, since it's in fact a "paper address" indeed (contrary to a "wallet" which stores multiples addresses, for ewample inside the wallet.dat file).

Lots of people are speaking about the safety of paper wallet. It's indeed easier than holding offline a wallet.dat file. 
But isn't it dangerous holding all your money inside only one address like the paper "wallet"?
There's definitely a certain danger to it. According to this book http://www.totalbitcoinsecurity.com/ there are two easy ways to improve its security:


Why put all your money in one paper address? You can split it up and put it in several paper addresses. This makes each address a less attractive target.
You can use BIP38 to encrypt the private keys. If somebody steals your encrypted private key he'll still need to know the passphrase. This is slightly related to two-factor authentication: in order to access the wallet, you need both the private key (typically stored in paper) and the passphrase, which you could remember or write down somewhere else.


Disclaimer: I have no relationship to the cited book. I simply read it last week.