Possible Clues:

• Saying 'I'm not sure that dress looks perfect on you,' e.g.
• Skill in saying the right thing
• People-person's skill
• Diplomat's trait
• In this was not broken with diplomacy
• What it takes not to say 'I see you've put on a little weight'
• ''Making a point without making an enemy,'' per Newton
• Asset for a diplomat
• Ambassador's speech is a little delicate
• Skill not displayed by asking 'Have you put on weight?'