They need to relate to the one before and the one after in an intelligent way. Lists of superlative claims with no substantiating evidence cannot be understood in context and cut no ice with anyone. The medium is in the message. If they have reached the third paragraph of your letter and glanced at your CV, you have already shown them that you can communicate. It needs to be implicit in your account of yourself, not stuffed under their nose as a grandiose claim.
Yucky claims are like unsubstantiated bullet points - they have no substance.
Pay Attention To Appearances People cannot help but be impressed by talented design and clever typesetting. Your choice of fonts and styles, however, is somewhat limited by the restrictions of email and online CV Builders. These are quite complex matters, beyond the lazy user, who will probably stick to the universal fonts and an ugly format in any case. If you want to make a subtle and sophisticated impression you need to start finding out about the technicalities by actually reading the help files and manuals you have so far taken for granted. Very few people that I encounter know that MS Word and Corel WordPerfect 9, for example, both allow you to embed the fonts in the document, or save files in the more universal RTF format.