I know the main reason people get venus is for her sleep skill. From what I've read on numerous posts she can only sleep two people when her sleep skill is maxed. The one in front and the one directly behind. (She may have to confirm this for herself though).

I personally think Venus is more suited to be a sealer. However whether you use her for attacking or sleeping she will need a lot of points added to int for each. Con is also important so she can take damage and still stay alive to continue to sleep or attack. I think agility would be more important if you wish her to be a sealer as well as wis since sleep does cost of a lot of sp! (So don't ignore the wis! Make it the third or fourth highest at least) No str required but I'm sure you know that already xD

Goodluck to her!!