Obama's weakness was his fastidiousness. He always wanted to avoid getting his hands dirty. Putin knew this and created the sort of problems Obama wished to avoid. He exposed Obama as a bluff.
Trump's weakness is his short attention span. He creates messes because he has no patience. Then he tries to bully people or take them to court to get the outcome he desires. He's going to bump his head against the constitution repeatedly. In the end, his bullying will likely also lead to armed conflict.