The ideal length of a sword in relation to a person's height can vary depending on the type of sword and the specific purpose or historical context. However, there are some general guidelines that can be considered. Here are a few examples:

1. Longsword: For a longsword, which is typically a two-handed sword, a common rule of thumb is that the sword should be roughly the same length as the person wielding it. This means that when holding the sword upright with the tip resting on the ground, the pommel (handle) should be near the person's shoulder level.
2. Single-Handed Sword: For a single-handed sword, such as a one-handed arming sword or a cut-and-thrust sword, the length can be somewhat shorter compared to the person's height. It is often recommended that the sword's length should be approximately two-thirds the length of the person's forearm, from the elbow to the tip of the middle finger.
3. Rapier: Rapiers, which are primarily thrusting swords, are typically longer and more slender. The length of a rapier can vary depending on the specific style and historical period. As a general guideline, the blade length of a rapier may be slightly longer than the person's height.

These are rough guidelines, and it's important to note that personal preference, fighting style, and historical accuracy can also influence the choice of sword length. Additionally, sword lengths can vary depending on the individual's physique and fighting technique. It is advisable to consult with experienced instructors or experts in the specific sword style or historical period to determine the most appropriate sword length for your needs.