I have never seen a DBDEFRAG utility for ArcServe VLDB, from version 6.6(?) up to 2000. Somehow they mixed up the filenames:
DBDEFRAG.EXE is the DBSTAT utility
DBSTAT.EXE is the DBIMP utility
There is no DBDEFRAG utility!!!!!!!
To make things even more difficult, the help message of the DB* utilities return the text you typed at the command line as their tool name...
E:\>DBdefrag.EXE /?
usage: DBdefrag.EXE [-?] [-v] [-b #] [-k #] [-nb] [-nk] [-nd]
...