I think legally speaking they are not "confiscating" your items. It's just that if you have these items with you, you're not allowed to enter the "secured" area of the airport. So they give you the choice:
a. Turn back, do not enter the secured area, take the train to your destination (or, as alfaman suggested, buy an envelope & stamps and mail the offending item to yourself).
b. Surrender the items to airport security: You give it away to them. They do not take it from you.
For all practical purposes, this may feel like a confiscation. But since legally nobody without a specific court order can take goods from you (except the tax man), they've implemented it as above.
Since you gave the goods away to the airport security, they are under no obligation to return the goods to you at any time. Although I know that some airports do provide a service to hold your goods in storage for you to pick up at a later date.
I've never had an item of mine "confiscated" but a few years back I went through the metal detector and it beeped. The security guy came up to me and politely asked if I allowed him to search me. I politely asked what would happen if I said "no". He politely told me "Well, you don't get to fly today, sir". "In that case go ahead and search me..." I guess with the forbidden items the same attitude prevails. You have two options: surrender the items or don't fly.