DISSIDIA ARCADE UPDATE:
Trueblade Seeker has just uploaded a translated breakdown of Exdeath's complete moveset and (almost) completely different, less defensive playstyle.
Like Onion, Ace, and Bartz, Exdeath falls under the Unique character class, and for good reason... 3 major ones to be exact. At any time, he can change between 3 modes (think stances in fighting games) to adapt to specific situations.
Power Mode allows him to play similar to other melee-based characters, and obviously gives him the most attack power of the other 3 modes. This is his default stance at the start of the match.
Debuff Mode gives him less attack power, but the final hit in any string of attacks he lands on his opponent reduce not only their overall stats, but also saps their bravery over a set period of time. The debuffs have a greater effect when his unique EX skill is activated during this mode.
Seal Mode gives him the least attack power, but the final hit in any string of attacks he lands on his opponent lock out their passive EX skills (not their unique ones). However, when his unique EX skill is activated in this mode, he can lock out even unique EX skills.
As far as his standard moveset, there isn't a single one of his BRV attacks that are useless anymore. Sword Dance behaves like an actual melee attack, but his new Groom Charge is the more preferred of the two, as it has super armor vs. magical attacks. Earthshaker is a great lockdown setup for team synergy. But perhaps the most improved of his old BRV attacks is his Vaccuum Wave. Once the most useless and slowest BRV attack in Dissidia history is now a competitively viable option, as it's as fast as any other standard melee attack and covers good distance.
As far as HP attacks go, Exdeath ain't without his classics. Delta Attack is back, but its properties have been changed. It no longer has a block effect, but its range increases the longer the attack is charged.
Reverse Polarity got a huge buff; you can now cancel from any BRV or HP attack immediately after hitting the opponent.
Almagest can now hit instantaneously on its own, but its range is now shorter.
Lastly, Exdeath's Omni Block returns, and has the same counterattack properties as before. Except now, when fully charged, Omni Block can even counter HP attacks!