Looks like you've started a reg war, which is always fun.

I 4bet bluff sometimes at 10nl in this situation against habitual blind 3 bettors and also 4bet a wider range for value against them too as they all shit their pants. Clearly I'm not the best player about, but what the 4bet/f does tell you is that villain is using his hud (assuming you 3bet often from the blinds) and adjusting to you, all of which indicates at least some form of competency.

Hand one: The fact you don't 5bet shove screams aces. Sometimes flatting the 4bet pre works if villain cbets in all 3 or 4bet pots and you know villain can make a laydown pre - it's not textbook poker but it does the job (you just need to be aware that villain WILL remember this!).

Hand two: I'm getting it in too. Pretty shitty if he has a set, but expect to see big pairs often enough, particularly given history.