I would go with a custom QStyledItemDelegate that provides a QLineEdit with the adequate echo mode.

Note that from a security point of view, the password shall be immediately encrypted and not stored as is.

You cannot obtain it from a QTableWidget.

Use a QTableView instead and create the editor with the default item delegate, using:

QAbstractItemView::itemDelegate and QAbstractItemDelegate::createEditor.

The latter will also return a pointer to the editor.

Then you can have your own QLineEdit, with EchoMode.

Having said that: simpler would be using the approach in https://stackoverflow.com/questions/11056245/pyqt-using-qlineedit-as-cellwidget-in-a-qtablewidget, i.e. setCellWidget(QLineEdit()), if you don't want to do it "properly" with an item delegate. It will then stay as a QLineEdit even when not being edited, I don't know if you care.

What are you using in QTableWidget?

For QLineEdit you can change the property setting EchoMode

[edit: koahnig] Just saw that the post is under "Qt for Phyton", which could be bit different. However, typically you look for similar settings in other languages.