Strength isn't Everything
Lilith is the best family member to use for the second part. Find Lilith's Phase Ring in the northeast room and use it to sneak past monsters and barriers. Some monsters, such as Treants, are incredibly tough to kill and sometimes are just not worth the trouble to wake. Sneak past them instead and save your hearts for more critical battles.
The Ancient Forest
The forest is dotted with lots of flora and fauna which will confuse you during the heat of battle. Keep your cool and fight or dodge as necessary. Remember to pick up the Bomb before you leave.
And a Tale of Fire and Ice...
Three more Shards await! We're not going to give away everything! It's more fun for you to figure out the rest of the game on your own. A hint is that for the third and fourth Shards you'll have to travel back and forth between two different areas in order to advance. Good luck!