User blog comment:ClariS/Unofficial PBE Patch Notes (1.0.0151)/@comment-83.196.51.137-20121102093716/@comment-4022742-20121102123242

If your main damage item and main survivabillity item gets combined you wil have an extra free slot for either more damage, survivbillity or utillity. Without a support this is kinda needed on TT.