whenever I look in JEI, or try crafting a crystal sword myself, the attack damage it shows is only 6.5. This has been the case since the first 1.15 alpha and is still present in v1.15.2-1.12.9. I am not sure if this is intended since 6.5 is an average damage number for swords, however axes still do the full damage they did from the 1.12 version.