Quick sword is a technique that utilizes Link's shield to grab the sword on the shore before the owl begins talking to Link. This occurs because the shield has a hitbox that has a farther reach compared to Link's body. There are currently two ways of doing quick sword, one faster than the other.
This method is the easiest. Simply approach the sword from the west while holding the shield out. Once the owl begins talking to you, mash through his text until the last text box. Begin holding the shield button and right, ending the text and grabbing the sword before the owl leaves the screen.
Note that it does not actually matter what height you approach the sword from - so long as you walk right and hold the shield out before and after the owl begins talking to you, you should always grab the sword before he leaves the screen. However keep in mind that approaching the sword while Link is in the water is slightly slower than walking on the shore, by a few frames.
The damage boost method is a bit harder, however it almost saves 2/3rds of a second compared to the above method when done optimally.
Approach the sword from the north. Damage boost off of the urchin, towards the sword. Shortly after the damage boost, begin holding right and the shield button. If performed correctly, Link should grab the sword before the owl begins talking.
Most runs that utilize S&Q dupe rupees on Toronbo Shores in order to get free bombs and magic powder. The general route goes like this:
After this, most routes vary. Some runners S&Q and collect the remaining rupees in the grass patch east of Tarin & Marin's house. Others go west after killing the three urchins and dupe off of the octorocks, S&Qing after duping off of the octorock on the cliff side. Both routes have no real time differences between them, and so it is simply preference.