I am sorry, but it is almost impossible to derive a Japanese forename based on "婉慧"
Truth is, the character 婉 is so rarely used in Japanese forenames. Sorry, but I've tried looking this up.
As for websites, check these out:
「女の子の名前辞書」計画http://www.dd.iij4u.or.jp/~ume20/f_name/
The DB is now closed. However, you can still download the data file for reference.
「猫の名前人の名前」 http://www.geocities.jp/nekononamae_hitononamae/index.html
I use this web for second opinion, esp. when the first one is not available.
「日本人のような名前 女性版」 http://cgi.members.interq.or.jp/mercury/p37/name/index.cgi?gen=0
I never really use this, but it's in my bookmark.
Hope that helps.