Been wanting a prybar to go with my copper EDC stuff for a while but I was worried copper wouldn't be strong enough. Found this old wrench on ebay for $10 and modified it for my needs. Left one of the wrench jaws on there so there's two ways to use it as a prybar. The spike end is rounded enough to probably not tear through a pocket but tapered enough to splice rope or tighten knots. Ended up being 5 1/2" which is a nice size.
https://en.wikipedia.org/wiki/Beryllium_copper
Inhalation of dust, mist, or fumes containing beryllium can cause chronic beryllium disease, which restricts the exchange of oxygen between the lungs and the bloodstream. The International Agency for Research on Cancer (IARC) lists beryllium as a Group 1 human carcinogen. The National Toxicology Program (NTP) also lists beryllium as a carcinogen. Copper beryllium alloy containing less than 2.5% beryllium (in copper) is not designated as a carcinogen.
This is interesting, what is the rope end used for and why do beryllium copper tools exist?
As Peppycito said, they don't make sparks, which is important if you're working somewhere that could have explosive fumes. The lanyard is traditional for sailors' tools to prevent loss as well as dropping it on someone below. Mostly decorative now but it's convenient to be able to let go of the tool if you need both hands for something.
They don't spark when hit against stuff. Presumably the rope is for not dropping it in the lake.
What do you carry on a daily basis?