Ave sodales,
Let consider a Maga descending from the legendary Melusine, illustrated by the Mythic Blood Virtue.
Now that Maga need to sleep plunged in water, or she cannot recover from her fatigue.
How would you illustrate that ?
With the Baneful circumstances Flaw (RoP:TM) ?
Or with a Greater Malediction Flaw ?
With a Lesser One ?
I would say a Greater Malediction - as most places won't have a bath tub and trying to get a barrel full of water for your Gifted friend whenever you stop for the night will cause people to ask questions, this flaw makes travelling amongst mundane society very difficult. It also makes travel through dry regions (like southern Iberia, mountains, much of the Levant tribunal) extremely hazardous.
Of course, your saga may vary - if your covenant is based on a ship or in a very remote region with streams everywhere then this is probably only a Lesser Malediction.
Considering it is solved with 2 level 5 spells, I would say Lesser Malediction.