The phrase "secondly it exposes vulnerability" suggests that there is a vulnerable aspect of a situation that is being revealed. To express this same idea using synonyms, one might say "additionally, it uncovers a weakness," "furthermore, it highlights a flaw," or "in addition, it reveals an area of fragility." Each of these phrases conveys the idea that there is some aspect of a situation that may be problematic or uncertain, and that this aspect is being exposed or made visible. Using synonyms can help to add variety and nuance to one's writing while still conveying the same underlying message.