I love this ability, when I farm it makes me nearly impossible to hit. When fighting Tremor Ram I'll get hit once per fight even though it's easy prey, and it'll do 30 dmg, about as much as decent challenge (even though mandy's don't hit for that much, but they don't count...).
Yes, treasure hunter II is one of the few traits that shows when an upgrade becomes active. I'm not sure why... maybe it behaves under different rules than TH1.
I may be wrong, but I don't recall this being in my list of Job Traits... I remember reading that I got this at 30 but thinking after I reached 30 'hmmm it doesn't show maybe it just shows as the first one "Evasion Bonus"'.
none of the job traits that you earn increases to at higher levels show up differently in your traits list when they improve, but there is a signigicant difference
That appears to be the only one, or one of the only ones that does indeed change the name when you recieve the upgraded version.
Fast Cast, Evasion Bonus, Clear Mind, Max MP Up, Magical Defense up, etc.. all of these will never change what they say from the first time you get the trait all the way to endgame when the trait is as high as your job/subjob allows. For instance, my RDM at 62 has Fast Cast 3 plus the Fast Cast bonus from my AF hat; yet under job traits it simply says 'Fast Cast'.