I disagree - he's a less bad case than his mother, but he's still got it and I'd argue the contrast is in part of what makes his relationship with his mother so fraught at at times.i wouldn't say he's obsessed with the Druuchi really, that's his mother. He actually dislikes the obsession with them, considering his relationship with his parents.
How focus works:
All Elves are a passionate, focused group, even obssessive in the worst of cases: the Long March, Arathion's single minded determination to restore the Dragon Armour of Aenarion, and Malekith's grasping, reaching, bloody desire for Ulthuan all stem from this same source. Vardanis is relatively mild in his case: he can put aside his Focus, for a time, to work on some other, potentially more immediately important, work but at the end of the day he has projects and obsessions, as any elf should. If they are not worked on he will get twitchy and irritable until eventually sacrificing the possibility of some other work. The longer he has gone without doing work related to a focus, the greater the odds of a meltdown wherein Vardanis will take a certain amount of AP and do some work to soothe said Focus. For the sake of all our sanity, this will happen in Turns proper rather than Turn results: He knows himself well enough to keep from making a promise then failing to keep it.
Vardanis' Focus:
FocusPrepare For War: You have neither forgotten nor forgiven the Druchii; and you will defend your home from them, no matter the cost.
Vardanis has a pretty good grip on his and by elven standards his obsession is milder because he has decent self-control and also because he's still on the younger side. That doesn't change that his obsession is literally baked into the mechanics of the quest where if he spends too long without doing something that soothes it, he will have a meltdown.