What is the most important skill a good business analyst should excel in?

The most important skills his ability to communicate with in and outside organisation..

The most important for a business analyst is to have good grasping power to understand the words of the client or communicator he/she is facing. A business Analyst works to take requirements from the clients. BA interacts with the clients on phone calls or visit him and creates BRDs (Business Requirement Documents) as per the requirement of the client. The created BRD is sent to the client to be checked if it really meets his explained requirements. If it captures well his all requirements as were explained to the BA than client gives approval to start developing his project/product. If still something is missing than BA has to work back on his document (BRD) and sends it back to the client. Approval of client is required first to start the development of the product. After getting approavl we start planning like cost estimation, Scheduling etc with the co-ordination of management team. We prepare cost estimation etc and take approval from the client in written means on mail. BA gives a presentation to his developers who are going to work on this project. The developers work to develop the same required product as mentioned in BRD. If its all happening in some IT Company than its good for a BA to have some technical knowledge like Computer langauges or shud have a software back ground. After the development BA tests the product which is called UAT (User acceptance testing) and it is done before the delivery of the product. If the product is ready to deliver than gets delivered. 

If some enhancement is required in some existing functionality of the product/software than the process is same but the document which is prepared for this requirement is called FRD (Functional Requirements Document). 

So for a BA the required skills are the followings-

Communication Skills

Presentation Skills 

Strategic thinking Skills (Should have the ability to give right suggestions, and self control)

Technical Skills

Buiness analyst play the big role in organization and some of skill shall be available

  Technical skills

Communication skills

Presentation skills

Negotiation Skills

Strategic thinking Skills

and the ability of improving

several.. give babok content a read