As the title states. Diawata using melee mods is capable of equipping tennokai.
However, it's pointless to do such a thing, due to using arch-melee combat, it lacks a heavy attack option. Meaning Titania is unable to proc it.
I think it shouldn't be possible for the mods to be equipped, or for Titania's stance and Diawata combat to be updated so that such mods can be used.