As a collector of WW1 debris found (by myself ) on battlefields, my reccomendation is to never touch or (worst) pick up anything that you do not know exactly what it is (including uncommon variants) and why it is there.
Some items could look innocent and still be lethal after one houndred years. Others could look extremely dangerous but would never explode.
I left untouched several findings that have a big value on collectors' market, and I do not regret having left them on the ground (well, actually in the ice), because I did not know enough about them to feel safe at handling. My life and that of my beloved ones comes well before any "collector's fever".
Luckily I learned a lesson when still a boy: I picked up a small brass tube less than 1 x 6 cm. It was a WW1 era detonator for mining works, ready to explode if simply hit with enough force. It wouldn't have killed me, but i'd have lost fingers and possibly an eye if not warned on time. As said by others, it made a nice "bang" when set in a fire by a competent adult.
By the way, I am more interested in equipment and personal belongings rather than in any kind of explosive device. Fact is that ammunition and unexploded (or even unused) handgrenades and shells are much more common to find than, say, a pair of glacier sunglasses, an intact glass bottle or an empty MG magazine.
The shell in the picture below is a "must have" for A-H shell collectors , but is still there in the ice... armed and ready to kill. It simply hit the target with a very low angle of impact and disappered under metres of snow. A good picture is enough as a souvenir.
