According to diskpart, a disk has four partitions:

Partition 1 - Recovery - 11GB
Partition 2 - System - 100MB
Partition 3 - Reserved - 128MB (MSR / OEM Partition)
Partition 4 - Primary - 464 GB

The four volumes are listed as:

Volume 0 - C - Blade - NTFS - Partition - 464 GB - Healthy -
Volume 1 -   - Recovery - NTFS - Partition - 11 GB - Healthy - Hidden
Volume 2 -   - SYSTEM - FAT32 - Partition - 100MB - Healthy - Hidden
Volume 4 - C - Blade - NTFS - Partition - 464 GB - Healthy - Hidden

More details:

• "detail partition" with Partition 3 selected claims that no volume is associated with the partition
• "detail partition" with Partition 4 selected claims that only volume 4 is associated with the partition
  
• "detail volume" with Volume 0 selected displays a list of attributes, plus volume capacity and free space
• "detail volume" with Volume 4 selected displays a single attribute - offline: no
• Removing or setting the drive letter of either Volume 0 or Volume 4 results in the change being mirrored to the other volume.
• The above information was obtained after booting into a Windows PE shell.  Diskpart does not show Volume 4 when running Windows 8.1 from the primary partition.
• Disk Management in W8.1 does show the duplicate volume entry as a Healthy OEM Partition (465 GB). However, it does not indicate the existence of Partition 3 in the disk view.
  

Problems resulting from misconfiguration:

• Disk Manager does not permit management actions on volumes (context menu shows only "help" entry, window menu entries are all disabled)
  
• BitLocker is unable to encrypt the volume, complaining that it is hidden.

Otherwise, the system runs just fine so far.  This is a new 2014 Razer Blade. (Have verified that another new 2014 Razer Blade has the exact same problem, so it's something that Razer misconfigured.  Their support isn't terribly helpful, unfortunately.)

• Edited by tvald Saturday, February 07, 2015 12:38 AM formatting

Screenshots attached, apologies for the coloration.  This is definitely an OEM configuration thing, but Razer hasn't been helpful.

As mentioned in the OP, the problem I'm actually trying to solve is that BitLocker can't encrypt the primary volume, but instead tries to encrypt the misconfigured MSR associated with C: (and aborts, complaining that the selected drive is hidden):

Hi,

Have you tried to contact OEM support to see if this specific settings is coming from its manufacturer? And we need more time to do research for you. Please give us more patience.

tvald,

Based on our research, we would like to provide the following hotfix with you. These hotfix is for Windows 8.1 and can updated the storage related files to the newest edition. After installing these hotfix, please restart the machine. After uninstalling the hotfix, please test how the issue goes.

===========================================================================================

Package: This is to upgrade NTFS.sys.

 

KB Article Number(s): 2996802

Language: All (Global)

Platform: x64

Location: (http://hotfixv4.microsoft.com/Windows%208.1/Windows%20Server%202012%20R2/sp1/Fix524134/9600/free/480025_intl_x64_zip.exe)

 

Package: This is to upgrade Msiscsi.sys

 

KB Article Number(s): 3000123

Language: All (Global)

Platform: x64

Location: (http://hotfixv4.microsoft.com/Windows%208.1/Windows%20Server%202012%20R2/sp1/Fix524132/9600/free/479758_intl_x64_zip.exe)

 

Package: This is to upgrade MSDSM.sys & MPIO.SYS

 

KB Article Number(s): 2914743

Language: All (Global)

Platform: x64

Location: (http://hotfixv4.microsoft.com/Windows%208.1/Windows%20Server%202012%20R2/sp1/Fix525821/9600/free/479581_intl_x64_zip.exe)

If there are any concerns, please feel free to let me know.