since they changed some parts of the password policity settings i dont think that it is possible to let a password field open a numeric keyboard. maybe you could try to go to the numeric keyboard anotherway round by just giving the it a diffrent input type like
<input type="number"/>
<input type="tel"/>
if this not works you could also try to use
<input type="text" pattern="\d*">
by giving the input type a simple text and forcing it to open the numeric keyboard with \d* like you already tried it in your code
maybe this link could be helpful for further information:
https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/KeyboardManagement/KeyboardManagement.html