# [Retina], <s>113</s> <s>81</s> <s>80</s> 77 bytes

    M1!`.+[A-Zz]|Nev?|.*sk|M.ss.s?|M[io]n?t?|[AFIOUW][^o]|Te.|.+
    \B.*(?=.)
    
    T`l`L

[Try it online!] Includes all 51 test cases. Saved 32 bytes by appropriating @JörgHülsermann's regex that finds the second letter (with a tweak to support DC; edit: saved 1 byte thanks to @JörgHülsermann). Saved 3 bytes by switching to @SteveBennett's regex from his comment to @HPWilliam's answer. The other letters are then deleted and the string uppercased.

[Retina]: https://github.com/m-ender/retina
[Try it online!]: https://tio.run/nexus/retina#TVDRbtswDHzXV3gPA7oWM7APGIwsQVuvdTJsaYMtzRDGZmPCshiIclMX/veMcgusgCAeRerIu49nV9tT8eXDNr1YTz7/edkMc3zKhvRcmqFIRVLJhmJNvHFZyIb15DJf3K0267@8GZaYDumFefiWnp9lX9NPxiy3dnt7Os1IgqcyJPyYTNl27Y7ATCzsoB2jNBo8vbCLsQEnIGYKlh7ZO23VP@yhYgXOYRmo7IKZoYUjeDSXWqQKzBWy32v3tT4TmbyCmk1uLTkmMbmrCJQ/5yOYm9cRN@hCVza9ueWOZCwXQA719r0FVykQgbLuBEMQU1BZ0x6cAt1DOGg/icRzONCIufMK2IVINsedH8WphVDFcEyuoT1ITbp3zL6jF@xHWOAzlTzC3@wbM2cf6mQKnlUBvKUzaOLURU1sFo1VhergwuOenfmBzklvnyBa9rPmCpNcRhW/uHtP9Zq@US0xShFERc/qyV2A2tyjb1WDuSd1NNKtQHd2@6BjVigh@V8gKdkJ6XvPrbb8Aw "Retina – TIO Nexus"