Merry Meet, @azalyn! 
Yes! While I wouldn’t say they are necessarily “dangerous”, it’s true that people used to be afraid of Eclipses. They were seen as a warning sign.
As far as I know, eclipses are not meant for spellwork or manifestation. Instead we just sit back, relax and reflect.
Eclipses only occur once in a while so it’s a good opportunity to look back at the past 6-12 months. Whether it’s about lessons learned or wishes that came true, we clear the path and open ourselves to new things that will come our way.
Follow this Lunar Eclipse Candle Ritual to explore your Shadow during the eclipse
Having said this, everyone’s path is different and you may have a different interpretation.
Some Witches see the lunar eclipse as a full cycle (Moon appearing and disappearing) 
in one night so that gives it a very special power.
.:｡✧ﾟ ﾟ･ ✧… * * .:｡✧ﾟ ﾟ･ ✧.｡. *
If you really want to cast a spell during the lunar eclipse, I would recommend something related to closing a cycle, like a Cord-Cutting Ritual or a Spiritual Cleanse to mark the beginning of something new.