Ki charging (pressing 1+2+3+4 simultaneously) is normally used as a taunt during the end of the round and is usually frowned upon in most Asian countries. Seeing someone Ki charge in normal play is a rare sight and is usually limited to Jin and Leo players who have strings with charge options available. Both characters have additional strings and properties post charge that can hurt a lot. The major benefit of Ki charging is that attacks performed after the charge are CH whether or not the opponent is attacking or not, though the opponent can still block. The major flaw is that you can't block and all attacks against you are CH as well. Risk versus reward, the opponent definitely has the advantage, but it becomes a very deadly game of cat and mouse as both players will be trying to land the first blow.
Ki Charge System:
Unlike most 2D fighting games, Tekken has no block damage by default (often refered to as "chip damage") therefore in order to knock out your opponent, your attacks must actually hit the opponent. A little known side effect of Ki charging is that all attacks that are blocked by the opponent will take a percentage of the blocked attack as damage, essentially making the attacks do chip damage. This number is roughly 10% of the damage that would have been taken if the attack wasn't blocked and as long as the player's attacks are blocked, the Ki charge persists until it's time runs out. As I've already stated numerous times, one of Dragunov's strongest points is that he can continuously pressure the opponent without giving up too many frames. Couple this fact with being Ki charged, he can essentially chip away his opponent while retaining a slight frame advantage making him nigh-invulnerable to retaliation.
Nice to Knows:
As I've already stated, Ki charging persists as long as the opponent has not been hit, hits you, or time has not run out. A recent change to T6 is that throwing the opponent (or being thrown) will allow the Ki charge effect to persist as long as time is still available. This makes throwing a valid, although very dangerous, strategy for conserving your Ki charge.
Ki Charged Tactical Moves:
iWR 2 - No two ways about it, you're most likely going to be using iWR 2 to get frames and corner your opponent. Launch on "normal" hit and +frames and chip on block.
f,f+2~1+2 - JF Sparks, comes out slightly faster and is inescapable.
b+1 - While not the best option, b+1 gives full combo on hit and can be used as keep out.
d/b+3 - High crush, low that attack throws at clean range and trips at near max range.
qcf+3 - Same risk with higher reward, high and later mid crush property frames can save your ass if your opponent goes on the offensive while you're charged.
Ki Charged Tactical Strings:
1,3,2~1+2 - A combination of chip damage and the "JF" grab, extremely risky.
d+4,1,3 - Since the entire string is NCc and W!, this is a strong low option.
d+4,4 - Similar to d+4,1,3 except slightly lower damage and W! directly to their back.
b+4,2,1 - Good damage and is +4 on block, the same risk with much greater reward.
1,3,1,2,4,1+2 - Dragunov's strongest chip damage string, fairly safe w/ push back.
1,3,1,2,1,1,4,1,3,2 - Same risk as his normal 10 string but with better reward, possible to stop the string before the last hit for manual bind if W!.