Thank you for playing the demo!
You can turn off auto-equipping in settings, though if your class has two crystal slots, they are more suited for extra skills/casts, and not very good for a melee combat. Though, I understand why would you want to try them in melee anyway.
For weapon blocking Trinkets are good, they go in off-hand slot, that will let you block with a main weapon and most of classes can use them, expect classes with crystal slots for offhand. I think I can finally make it available for all classes, I like variety in builds.