What is this speaker cable connection?

I would just add some heat shrink insulation to insulate the portion below the spade. Heck, even wrapping electrical tape should do the trick.
Bob

I meant to type:

Key to these is that the core is copper.

+1 gdnrbob, the really easy clear solution is with a simple wrap of electrical tape.  No reason to listen to those that get all high drama about it, the connectors will likely work just fine.  As mentioned above, if they are too long to connect from the bottom, connect from the top.  Also, can't beat the price.

you can remove them, and put banana plugs on yourself

Spades are much better, connectivity-wise, in my opinion.
Bob