When you looking at a shield in the creative mode. It still showing metadata value. Items that don't use metadata usually do not display their data value.
MC-88465
Shield still have metadata
Resolved
Fixed
5
Confirmed
Minecraft 15w37a, Minecraft 15w41b, Minecraft 15w42a, Minecraft 15w43c, Minecraft 15w44a, ..., Minecraft 15w45a, Minecraft 15w46a, Minecraft 15w47a, Minecraft 15w47b, Minecraft 15w47c
Minecraft 15w49a
Retrieved
Confirmed.