This treatise although applicable to most fencing disciplines is really intended for those that will be taking part in Elizabethan fencing. The style of rapier and dagger is not radically different from say smallsword but the lines of attack and the defenses used in rapier will look "odd" when employed with a smallsword.
No matter the age (Gwylym's son Rhys in a production...), one may learn the art of fence and with proper training may be safe.
The main thing to remember when performing is that you are working with a partner not an opponent. I have found that many individuals who are good combat fencers, make poor to intermediate actor combatants. The reason is the philosophy of what they are doing. True combatants want to instinctively hit their "opponents." The actor does not want to jeapordize the show. If you will be training for a performance, try to avoid doing any combat fencing. Change the underlying philosophy and do not "taint" it.
As a final picture you may see young Rhys watching part of an act called the Cat Fight where two women fight over a man (supposedly married to the both...).