Death’s Sword
It can be said that the rework at the beginning of season 6 has caused Death’s Sword to nearly disappear completely. Previously, Death’s Sword could provide Attack Damage based on the number of units the champion had that participated in takedowns. However, after being adjusted, this item now only grants a fixed amount of Attack Damage based on level and does not give champions the ability to break through in terms of damage. Clearly, when compared to other items like Infinity Edge and Giant Slayer, this item is significantly weaker.

Furthermore, the component items needed to assemble Death’s Sword (2 B.F. Swords) are extremely expensive, making it rare for players to craft this item. Combined with the fact that it does not provide a breakthrough in damage as mentioned, players have even fewer reasons to aim for crafting Death’s Sword. This item may only be strong in certain compositions (such as the hyper-roll Ezreal team), but that alone is not enough to make it a viable choice in the current meta.
Rapid Firecannon
As the first half of season 6 comes to a close, it is easy to see that many melee carries in Teamfight Tactics do not synergize well with Rapid Firecannon. Remember that most champions of this type are in the Challenger class with dash effects towards opponents, further diminishing the value of Rapid Firecannon. Not to mention the prevalence of champions with area control, making Quicksilver a much better defensive option.

That said, Rapid Firecannon is not a “100% useless” item as it still proves to be quite strong in the hands of Talon. However, this only makes Rapid Firecannon weaker in season 6.5 as Talon is an Empire champion and is among the targets soon to be removed by Riot. Perhaps Riot needs to add a champion that can effectively utilize Rapid Firecannon like Talon in the upcoming season 6.5 to compensate for that loss. If not, they really need to find a way to revamp this item.
Zz’Rot Portal
Even before season 6 began, Zz’Rot Portal was already a weak item and not very popular. After the launch of season 6, this item became even weaker as the effect of provoking opponents was no longer unique, since the Guardian class also possesses it. Combined with the presence of valuable component items that are fiercely contested, the rate of players crafting Zz’Rot Portal in the current season 6 has decreased even further.

Essentially, the operation of this item goes against the goal of tank champions. This item requires the owning champion to die to be effective, whereas the goal of tank units is to survive as long as possible to protect the backline. Therefore, Riot Games truly needs to consider completely reworking, or even replacing this item with another one in the upcoming season 6.5.