What does mean VarType(aVariant) = 273 (or $111)? It's undocumented variant type. VarTypeAsText(aVariant) returns Expression illegal in evaluator error.
From the source code of the system unit:
const
{ Variant type codes (wtypes.h) }
varEmpty = $0000; { vt_empty 0 }
varNull = $0001; { vt_null 1 }
varSmallint = $0002; { vt_i2 2 }
varInteger = $0003; { vt_i4 3 }
varSingle = $0004; { vt_r4 4 }
varDouble = $0005; { vt_r8 5 }
varCurrency = $0006; { vt_cy 6 }
varDate = $0007; { vt_date 7 }
varOleStr = $0008; { vt_bstr 8 }
varDispatch = $0009; { vt_dispatch 9 }
varError = $000A; { vt_error 10 }
varBoolean = $000B; { vt_bool 11 }
varVariant = $000C; { vt_variant 12 }
varUnknown = $000D; { vt_unknown 13 }
//varDecimal = $000E; { vt_decimal 14 } {UNSUPPORTED as of v6.x code base}
//varUndef0F = $000F; { undefined 15 } {UNSUPPORTED per Microsoft}
varShortInt = $0010; { vt_i1 16 }
varByte = $0011; { vt_ui1 17 }
varWord = $0012; { vt_ui2 18 }
varLongWord = $0013; { vt_ui4 19 }
varInt64 = $0014; { vt_i8 20 }
varUInt64 = $0015; { vt_ui8 21 }
varRecord = $0024; { VT_RECORD 36 }
{ if adding new items, update Variants' varLast, BaseTypeMap and OpTypeMap }
varStrArg = $0048; { vt_clsid 72 }
varObject = $0049; { 73 }
varUStrArg = $004A; { 74 }
varString = $0100; { Pascal string 256 } {not OLE compatible }
varAny = $0101; { Corba any 257 } {not OLE compatible }
varUString = $0102; { Unicode string 258 } {not OLE compatible }
// custom types range from $110 (272) to $7FF (2047)
See the comment at the very bottom of the list. In other words, $111 is a custom variant type. Exactly what it is depends on the code that defined that type. Code that is not in the RTL and is presumably in your program.