Was under the impression the link would form an actual "you shall not pass!" line.

Instead it seems it just functions as one yrden across a wider area, basically a waste of vigor since it's not difficult to get enemies into a single yrden. They either don't "see" them or don't have the AI to go around them - they just go straight for you so you just stand behind your yrden.

I took this talent toward the very end of the game just because I wanted to see how it worked before trying a build including it earlier on, but it seems utterly worthless.

Hmm it should create a line between the 2 if you have the skill that links the traps together. Try spreading them out a bit more maybe.

It creates the line, but when they run into the line it functions as a regular yrden trap, not as a barrier. It says in the talent description it should prevent them from moving between glyphs, but instead it simply functions as one yrden made from two - a single enemy will get trapped when they touch the line and then the line disappears.

The description is somewhat vague but I got the impression the line would function as a barrier until an enemy ran into either of the yrdens creating the link, or until one of the yrdens expired.

It seems useless in it's current implementation regardless.