This artifact is bluelined a sword. It is interesting, but not dominating. First off, this artifact can be used by any champion, and that champion becomes worldless. This means that they are no longer a Forgotten Realms champion (for example), but without world. This even means it is not AD&D.

A champion always gets a world bonus, as opposed to a truly worldless champion, which would never get a world bonus. Therefore, Blackjammer’s Cutlass effectively always gives the attached champion nine adjusted level (+6 icon bonus, +3 world bonus).

The last line, making the attached champion immune to artifacts attached to a champion from a different world (like a Dark Sun artifact attached to a Dragonlance champion using an Ego Coin (419/2nd)) can have some suprising uses. For instance, if the Wand of Orcus (1/AR) is attached to a non-AD&D champion, it suddenly is worthless against Blackjammer’s Cutlass.

This can be very useful against artifacts that attach to champions of any sort or specific types. Examples would include the Axe of the Dwarvish Lords (2/AR) only working when attached to an AD&D champion, or The Winner's Cape (520/4th) not working in battle ever, since there are no “TSR” champions.

Generally, battle focused cards that don’t instantly win combat don’t make it into tournament decks, but it is very possible that this card will make it into many fun decks, especially since it can fit into any deck, and might specifically hurt mongrel type decks.