It is not the sword itself that talks to you. You don't need any particular strength to remove the sword in the stone (don't recall the requirements to use it). However, if you remove and keep the sword, many in the Dark Forest will be killed. You can either remove and replace the sword, or wait until you have done all quests in the Dark Forest, then remove and keep it.
BD is set 20 years after DD, and does continue some of the story of DD, but is not a direct sequel.