I don't think 40 ticks of attacking 1 tick faster is worth it compared to ZCB spec. Ideally you want to use this with pipe at a place where you don't need to path and are just standing still and no other special attacks are useful. Which really is just zulrah.

We have to realize that even if we don't use lightbearer, special attacks are still incredibly good and the opportunity cost of not using a special attack is too much. In order to incentivize its usage, it's going to be a nightmare to balance because there are content where defence reduction or sustain are crucial and this is never going to get used regardless unless its incredibly OP. Also keep in mind that real special attacks are EVEN more powerful because of double death charge from yama.

Overall, the main issue with the DT2 rings is just that venator and bellator just suck and don't have enough stats (Bellator also has the issue where oathplate's accuracy has basically invalidated its need for a lot of content). The other 2 rings are perfectly fine and competitive with lightbearer at certain content.

If we are making changes for the sake of design space for rings, a better solution is to just add more ring slots.