Siegfried uses slow yet powerful attacks, but because of his slow speed, it is quite easy to counterattack before he can even land an attack. His moves mainly consists of slashes though he does possess a few stabbing moves, but these aren't as effective as often as the slashes.
Siegfried's fighting style in this game is almost identical to Nightmare's with a few exceptions. He uses somewhat slow, but hard hitting attacks (although his attacks in Soulcalibur are a bit faster than they are in other Soul Series games). His stances where also introduced in this game (both he and Nightmare use them).
For more information, see Nightmare's Battle Style page
Siegfried's fighting style in this game is similar to his former alter ego, Nightmare's from Soulcalibur II. He has relatively slow attacks that hit very hard. His speed can be taken advantage of though, because some of his moves leave him open, and fast characters can easily get behind him to inflict serious damage. However, if his attacks do hit, they will hit for a lot of damage. He uses large, heavy swords called Zweihanders, which are better for crushing and slashing than for more advanced swordplay like Raphael's style. He is not built for stabbing, and most of his attacks are slashes.
Siegfried still plays in a similar manner as he did in III with a few changes that force players to relearn him. Siegfried is best when the opponent is just within reach as it allows most of his moves to connect with relative ease while keeping him out of some characters range. He has few moves that auto-Guard Impact so timing in attacks is crucial. Siegfried is mostly a high attack character with few low attacks, but the few he has are easy to use and activate relatively fast. Most opponents can side step his more powerful attacks so prediction is a necessity. Also his high damaging attacks usually leave him open either before or after the attack, making timing and prediction all the more important. Siegfried also has a few stances in which he changes his hold on his sword to use other moves. Most of his powerful moves involve shifting Siegfried's stance, which alerts his enemy to what he's planning.
Siegfried plays the same as he did in Soulcalibur IV, though he does have one new guard break attack which can be performed by inputting the R button (default control settings).