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Given current implementations, is there a wallet that I can use to scan a private key, then enter in the password as a PIN, and the wallet will send from the key and sweep the rest onto a key generated from the phone?
Android, obviously.
Also, what's the state of BIP-38 integration with wallets in general?
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Blockchain.info works well, exactly as you describe for BIP38 encrypted keys.
I switched to Mycelium in late 2014 and have had good experiences since then.
what's the state of BIP-38 integration with wallets in general?
It is actually quite good now. Only obviously missing wallet is Armory: https://github.com/etotheipi/BitcoinArmory/issues/131
(Armory pioneered many of these ideas with its own implementations, but it is not yet using standards like BIP32 and BIP38 which came later)
One can also use Bippy to work with BIP38 encrypted keys offline.
PS: I just added recommendations here for creating a paper wallet: How to download bitaddress.org to use offline?
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Mycelium is a well-reviewed Android wallet that seems to meet the criteria you've described.
