What you are looking for is hardware wallet like Keepkey, Ledger or Trezor. It is dedicated hardware wallet where you have to confirm any transfer of coins. The point is the private key can never leave the hardware wallet, it just sign transactions which you have manually confirm on its display where the coins going to be send.
absolutely i will agree with your opinion,that if you doubt to ether wallet(store your coin), you must transfer to another wallet like ledger or trezor,aside from that being alertness and awarness during transaction it should be ,to avoid also from mistake during process,