Try using the Qshell utility that is designed for data areas:
datarea -w /qsys.lib/sequenceda.dtaara $(echo '01/01/10')
See datarea – Read or write i5/OS(TM) data area for details.
However, it is not a good idea to be creating your own objects in library QSYS. It is especially not a good idea to be experimenting while creating objects in QSYS. Use a different library.
I don’t know anything about the arsdate command. You will need to tell us what arsdate does before we can help with that.