Using 'loftily' can imply you think you're better than others, which might be rude. She loftily claimed that no one else could match her expertise.
Pro Tip 2/3
Cultural Nuance
In some cultures, speaking loftily may be seen as disrespectful, especially to elders or authorities. In the meeting, his loftily expressed opinions were not well received.
Pro Tip 3/3
Social Context
Best used among friends or in informal settings where it's clear you're joking. He spoke about his cooking skills loftily, eliciting laughter from friends.