I will grant that the sword looks like a naval cutlass (although one from the nineteenth century) and that the object crossing the sword looks (to my aging eyes on my imperfect monitor) like a cat 'o nine tails. On the other hand, the sword could have been simply a symbol of Roman authority (as rendered by someone who had no grasp of the history of swords) and the “cat” a symbol of the scourging of Jesus.
I would tend to doubt a pirate connection.
I would have guessed that the skull and bones were a reference to the hill of Golgotha (“place of the skull”) where the crucufixion took place. There are quite a few symbols on the cross, itself, (flowers? crowns?) that have no “pirate” association of which I am aware. (The symbols above and below the skull do not look like anchors, to me, depite the bowed crosspieces.)
I agree that it was probably broken off some larger base. Do the vase and ewer atop the arms of the cross each have a place into which a candle could be inserted? That would indicate that it was originally free-standing.
Is there any lettering (aside from I.N.R.I.) on it anywhere?
I can’t figure out a “pirate” association (and the manner of the sword makes me think it was created long after pirates were “romantic” figures in the Caribbean–and after they had been pretty much exterminated).