Letting someone reserve a good Parry while making minor ones doesn't make a lot of sense, as Kromm points out. Allowing the warrior to delay and take his turn at a different point in the initiative sequence, on the other hand, should be fine. So if the Knight has BS 6, the Warrior BS 5, and the Skeletons BS 4, the normal order would be knight-warrior-skeletons-knight-warrior-skeletons-etc. Having the Warrior delay to BS 3, however, would change the order to knight-skeletons-warrior-etc, meaning he'll always get his best Parry against the knight. This does, however, encourage a sort of Delay-war - the Knight may then Delay to BS 3.5 so he goes after the skeletons, then the Warrior delays to BS 3.75 of the next round so
he goes after the skeletons, and so forth.
EDIT: Also, while this wasn't one of the intended use cases, this is a situation my
Initiative Overhaul can handle nicely. Well, if the system itself wasn't an unholy
pain to try and use, anyway.