d'art's snipeshot is good, but i think everyone overly-praise the skill. While it is nice that it gives a 20% atk n def debuff, it falls in 2 departments.

1. its in the b-slot for debuffs, and a good number of himes get atk n def debuff in the b-slot. (although it may only be a 15% debuff)
2. im not sure if its intentionally or not, but snipeshot can get overwritten by 15% said debuffs so it can go to waste...

thou by the sounds of it, ur mainin wind right now, so cybele debuff should be enough for now. u'll definitely benefit more from ambush or other a-slot debuffs. (personal, opinion go mordred she's practically a bread n butter 3rd soul)