Alright, so Boronda is an addition by the translators. Both runes have the same name in Japanese, except that one is written in Kanji, the other in Katakana. We’ve seen this a lot but this is the only case that it happens within the same game, right? So obviously the devs wanted to make a distinction, but what did they have in mind?
1. These are different runes with the same name
The swallow rune is probably an example. Genshu’s (or Richard’s) and Kyril’s runes are totally different. You might say that it’s because the spells in Tactics are different, but don’t forget that Genshu’s rune attack is basically the 2nd lvl spell from the Tactics viper rune, except for the cheesy samurai animation. Suikosource even lists them as 2 different runes. However, I think the two great hawk runes are too similar, so…
2. These are the same rune with different effects
But then, what could be the reasons for them working different? One could be proficiency or physical preconditions like in the case of L.C.Chan’s and Wakaba’s white tiger rune. L.C.Chan, the martial arts master, has only a 20% chance of getting unbalanced from using it, while teenage student Wakaba has 50%. However, it would mean that since Jacques is more proficient, he can use it only once, and that doesn’t make sense (even though according to suikosource his rune hits all enemies while the other rune only hits all enemies within a certain area). Another reason could be the uniqueness of Jacques weapon. His bow gun seems to be similar enough to bows and crossbows so that it’s possible to make the great hawk rune work, but it’s too different to make it work the same way. Finally, perhaps his rune is a modified version of the great hawk rune, I mean specifically modified by some army rune master. This would explain why it is fixed on Jacques, and it doesn’t exclude the above mentioned reasons (character proficiency + weapon uniqueness).
"Within the four seas, all men are brothers" Shuihu Zhuan