Sign message description changes discussed in #bitcoin-dev

src/qt/forms/messagepage.ui

@@ -17,7 +17,7 @@
    <item>
     <widget class="QLabel" name="labelExplanation">
      <property name="text">
-      <string>You can sign messages with your addresses to prove you own them. Be careful to only sign statements you agree to with full details, as phishing attacks may try to trick you into signing access to them.</string>
+      <string>You can sign messages with your addresses to prove you own them. Be careful not to sign anything vague, as phishing attacks may try to trick you into signing your identity over to them. Only sign fully-detailed statements you agree to.</string>
      </property>
      <property name="textFormat">
       <enum>Qt::AutoText</enum>