Richard Hornsby argues
that GZ's martial arts training is admissible. His first argument is pretty good: that the state will use it in an attempt to show "Trayvon Martin was a small, unskilled, teenager who lacked the physical ability or capacity to overpower George Zimmerman." It very well may be admissible for that purpose, but that argument would seem to undermine the prosecution's credibility, since GZ had fight injuries and TM didn't, and W6 and W14 both have GZ on his back.
I'm dubious of the Hornsby's second argument. He says:
Moreover, the Florida Supreme Court has indicated in dicta that specialized training (such as Martial Arts) is relevant evidence notwithstanding its also evidence of bad character traits. ]Trease v. State, 768 So. 2d 1050 (Fla. 2000) (FN5. Evidence of proficiency in the martial arts and how to use a knife was relevant evidence against defendant in murder case.)
The linked case contains a footnote:
 Trease raises an additional evidentiary issue claiming that the trial court erred by admitting various pieces of alleged "bad act" evidence. We disagree. Evidence of Trease's proficiency in the martial arts and in how to use a knife, his threat to "cap" a police officer, his repeated requests of acquaintances as to whether they knew of any rich people with safes that they could steal from, and evidence that Trease lied to law enforcement officers about his use of certain drugs were relevant. See Bryan v. State, 533 So.2d 744, 746 (Fla.1988)(holding that the controlling issue in the admissibility of evidence is relevance). Testimony that Trease referred to himself as a law enforcement officer seems irrelevant, but it could only constitute harmless error. See State v. DiGuilio, 491 So.2d 1129 (Fla.1986). Trease also takes issue with alleged testimony that he referred to himself as a "gigolo"; however, the record shows that the trial court sustained Trease's objection thereto and provided a curative instruction to the jury, and that Trease did not move for a mistrial. We find no reversible error.
The cited case, Bryan v. State
, is about evidence that's indicative of a bad character but which was admitted for another purpose. For instance, in that case evidence of a prior robbery was admitted. The court said: "In the case at hand, the evidence surrounding the bank robbery was relevant to the issue of ownership and possession of the murder weapon by appellant." I don't believe Hornsby's claim is justified because we don't know why Trease's proficiency in the martial arts was deemed relevant.