Traveling w/a backpack containing pocket-knife, water, etc. Can't carry it on of course, but can I check it?

I've never seen a backpack come tumbling down through the baggage claim area, so I'm a bit apprehensive. Also, are there any of these types of requirements for traveling by train (specifically in Europe?) or are they are little more relaxed with that mode of transportation?

Backpacks are fine as checked in baggage. If you have concerns, you can request a large plastic bag (they provide them) for extra protection.

And a pocket knife would be fine if it's checked.

you can check the bag,if you try to carry it on they will take the knife and water from you and you wont get it back