I do this all the time. I would think you've discovered that Oracle's R-Tree Spatial Index does not support curves for geodetic coordinate systems and you need to get rid of them, correct?
While ArcCatalog won't load the layer, you can load it with sdeimport though the indexing step will then fail. However you will have a layer - the SDO_GEOMETRY will contain the curve features and the SE_ANNO_CAD_DATA field will contain the mysterious ESRI blob data (be not NULL). At this point you can inspect the SDO_GEOMETRY for the curve features but you can't do much about them as the Oracle Spatial utility SDO_GEOM.SDO_ARC_DENSIFY does not work in a geodetic context and Oracle will not allow you to transform them into a projected system. But you could identify them here if you just want to delete them or complain to the source about them.
So to densify them you need to backup a step and import your curves into a projected coordinate system that works for you in Oracle. Maybe a nice Albers Equal Area or such, your call. Anyhow once you load them in this manner you will again have the curves in both SDO_GEOMETRY and SE_ANNO_CAD_CATA. Now you can densify the SDO_GEOMETRY AND remember after you do so to set SE_ANNO_CAD_CATA to NULL as if you don't ArcSDE will keep reading the curves out of the BLOB. I believe the SDO_GEOMETRY is ignored when the BLOB field is not null.
Hope that helps.