thief only can have 8 th on body?

[Vashkoda]

wait so let me make sure im understanding this: u are saying its ok to be th13, so i can go over the 8 cap in gear and rock out?

The most TH you can apply with your first action on a mob is TH8, and this will always proc (this includes your gear, traits and gifts). Note that the messages you get about TH in the log are only for *upgrades* to the mob's TH level, which is why it will only comment about TH9 and above (*after* you've already procced TH8, which it won't leave a message about). TH upgrades are random, but you can increase the chance of it happening with SA, TA, higher TH levels of gear, gifts, and merited feint. So yes there is a point in wearing more levels of TH gear than just what it takes to reach the TH8 cap for the first action. However, people have observed limited returns in terms of drop improvements after TH4 or so, so it's up to you if you want to bother. Obviously, your damage output will also be somewhat limited when you wear TH gear, so if the NM is dangerous or you have a time limit to kill, it may not be worth it. Also, TH upgrades can take a white to happen (i.e., people taking 10 minutes to kill Behemoth just to get those last few levels of TH in). A compromise some thfs take is to just wear enough gear for TH8 for the first few hits (especially as you feint and SA and TA, improving the chance at a TH9 message), and then change back to regular gear. It's not impossible for further TH upgrades to happen without wearing all that TH gear, but it will be a lot less common. Again, the question is whether or not you believe those last few TH levels are worth it.

[Cyriack]

does anyone ever claim to get more drops or better drops with a little more th??

[Nyarlko]

does anyone ever claim to get more drops or better drops with a little more th??

You will statistically get more drops with higher TH procs. TH does not affect the quality or selection of what drops, only whether or not each drop slot has something in it.
EX: Proccing TH12 on King Behemoth will not affect whether you get a Defending Ring or a Pixie Earring since that slot is already 100% drop rate. Proccing TH12 WILL affect abjurations, hide, meat, etc. since those are not 100% slots.

[Folken]

Long answer: Maintaining the highest value you can (up to TH13) will result in the statistically highest possible proc rate. If you have a total of TH8, then you are going to have a very difficult time making it up to 12 (since proc rate is penalized if your current TH is less than the current proc,) while if you have TH13, you will have the best possible chance of making it to 14 since your proc rate will not be penalized at all (14 is assuming you have all the related job point gifts.)

It's still funny how SE said something like "More TH doesn't increase proc rate. Less TH will decrease it, though."

[Nyarlko]

It's still funny how SE said something like "More TH doesn't increase proc rate. Less TH will decrease it, though."

I believe that they should raise the base proc rate with the current gamestate. The vast majority of things die far too quickly to reliably get to just TH12, which makes the gifts feel rather pointless most of the time, even with the proc rate bonuses from gifts.