I'm a bit of a newbie so I haven't faced a titan yet, but I have had a werebeast. I think the thing with werebeasts is that you need to inspect the combat logs closely. Put anybody who had contact with it in a squad. A day or two before the full moon comes, individually station each one to the far reaches of the map. Burrow your citizens and close the main bridge (werebeasts being building destroyers...). Try to keep the possibly infected out of eye-contact with each other. When the full moon comes, take note of who is a were-beast.
After that, create a squad just for the were beasts. Build a hut without a door, and the entryway facing the edge of the map, near the edge of the map. A few days before the full moon, station them in the hut. Do *not* engage in training! (because if they spar while transforming it will cause a loyalty cascade -- learned that the hard way). Wait until they transform and then transform back. Cancel orders. You will probably not need to burrow your citizens unless you have some stupid visitor standing outside the hut (which can be fun!)
It is a bit of a PITA because the full moon changes from month to month (it is always 2 days earlier than the previous month). You can keep an eye on the moon icon in the upper right hand corner and when it goes to waxing start doing the mental arithmetic. Also if you get a siege you *must* send out the were-squad and lock the door until either they die or the full moon comes. If they survive until the full moon, it is quite entertaining.
I had a were-capybara for 2 years until I decided to unleash him on some undesired guests. For some reason I had one dwarf who ignored the burrows order and was slaughtered, causing a loyalty cascade. It's easy to contain at that point though because the fighting is outside. Just close the bridge until a winner emerges. In my case the were-capybara turned back and was slain by one of the "guests". I sent the militia out to kill him just in case he was infected, but they got caught up in the loyalty cascade. Closed the gates and waited -- 3 dead, 4 in the hospital... Another lesson learned.