Step #113 in the Expanded Vanilla list
Do not use the included esp! This is listed as partially working because a patch is required for this to work with OpenMW, see Welcome to the Arena v6.7 patched for OpenMW for the working plugin.
The following texture files need to be renamed:
Textures/TX_Arena_red_cuirass_1_NM.dds Textures/TX_Arena_blue_cuirass_2_NM.dds Textures/TX_Arena_blue_cuirass_1_NM.dds Textures/TX_Arena_red_cuirass_2_NM.dds Textures/tx_golam_blade_06_NM.dds Textures/TX_Arena_Cuirass_Valor_2_NM.dds Textures/TX_Arena_Cuirass_Valor_1_NM.dds
Please see the file renames guide for more information.