i gotta say those large fans are looking like they have lost their luster and starting to look almost silverish hue-could be the pics but is this the case? points to a potassium def, and given their age, most likely caused by high salinity in the soil. you know if u let the soil dry out completely before watering, this cause a huge increase in the EC which can block potassium.
and whats up with that slipperly looking leaf in the 2nd pic?