Just set it and unset it as you do for the ForeColor :
private void passwordLogin_Leave(object sender, EventArgs e){
if (passwordLogin.Text.Length == 0){
passwordLogin.Text = "Password";
passwordLogin.ForeColor = Color.Silver;
passwordLogin.PasswordChar = '\0';
}
}
private void passwordLogin_Enter(object sender, EventArgs e){
if (passwordLogin.Text == "Password"){
passwordLogin.Text = "";
passwordLogin.ForeColor = Color.Black;
passwordLogin.PasswordChar = '*';
}
}