I think you might be right.
Here are more pictures (with scale) where the text is easier to read
link
I think you can clearly read "Signal" "Recall" and "Delay" on it.
You can also read "N.E.C. Approx." with what looks like maybe a number after that. I'm guessing that N.E.C. might mean "Northern European Command" (related to NATO)
Under that you can read the stamp from the LOT number.
I read on the Dutch forums that someone at the bridge building engineers here apparently identified it as some kind of thunderflash thing that they use for recalling divers.
I also read that the diver's fingers weren't blown off. Only part of one of them was and I guess he's lost the top of his left pinky. The ring finger was badly mauled too but I guess that's ok. The explosion was pretty powerful though because from what I read it broke other bones in his hand. My guess is that the "delay" on the side of the thing probably meant that once the trigger was pulled out that there was a delay before it went off. In any event, he pulled the cap off and it didn't do anything for several seconds and then went off in his hand. It's pretty lucky he didn't slip it into his pocket when it didn't go off right away...
R..