Great. Suggestions for further additions:
Improved Trip: Lack of AoO from Roy on Tarquin's trip attempt in panel 2;
Hold the Line: Tarquin stabbing Belkar mid-jump with the arrow.
Just because he did 3 attacks on a full attack does not mean he can't do more. One of the reasons, as mentioned, may be his desire to keep up his disguise as Thog (who, so far, has shown a full attack of 3). And in general Tarquin has been very lax during this fight, not being dead set on destroying the Order at all.As per Tarquin's three attacks in 852, I've pegged his maximum level at 15 for now.
Another valid reason, also mentioned above, is that Tarquin may have a few levels in a non-full-BAB class (e.g. personally, I love a level of Cloistered Cleric, Swordsage or even Rogue on my warriors).
So, while we can be certain that Tarquin is at least level 11 due to 3 attacks, we can't be sure that he's not higher than 15. That would be ridiculous to assume, anyway, since Elan is 15, and Tarquin defeated him effortlessly at his own game (pun-duel).
Based solely on the attacks, I'd rather list Tarquin's level as 11+.