Mostly say, its just a mental mission to be humble and not greedy.
The Storytelling goes also in that direction. But if you go in that Rotworm Cave and trigger, that the spike sword dissapear, then you need to ask yourself, why it happened.
Not just accept it because the game is scripted.
Rumour is, when you trigger that spot, then ebb and flow comes and float the spike sword away.
Some say, there are other spots in rook, which need to be there at same time.
Old solution trys, was to fish the spike sword, when it dissapear.
Maybe it can be true, but the chance is for sure 0,001% maybe.
If you play tibia as rpg and follow the history/story, then you will see, that alot of Quests,Missions got parts and spoiler mechanics etc to give hints for something else. Some think, that The isle of Evil is connected possibly to that Spike Sword in Rookgaard.

Cults of Tibia, Forgotten Knowledge Quest and a few more quests, spoilers alot