Actually I would personally disagree, Shamir is and he's less experienced so Shamir would without a doubt be wrecked in sword combat. But that doesn't mean he can't be creative in his approach, as a tiefling you have the bodily weak points that an experienced fighter would know to take advantage of to get in a few good shots, but magically he can be over powered rather fast. I agree Shamir vs Kyvir is a poor match up, but with more experienced sword fighters it would be interesting to see them fight. Alexander seems to be more inclined magically than physically, so right now the only toe to toe fights I can see happening is Garuda cs Kyvir or Isilfarrel vs Garuda, since Garuda I would rank as the close second strongest magically and Kyvir out classing him physically but potentially not creatively. If that makes sense. Though that's just me speculating since you know your characters better than me and their limitations, I'm only going to step in if you start getting superman syndrome and never lose.
And just so we're clear, I'm not arguing I'm just having fun discussing.
Even with a creative approach, Shamir's magic is only good for (at least right now) healing minor wounds and transmutation, and he doesn't seem to have much ranged ability. So the fight would be very up-close and personal, which is where Kyvir accels.
Alexander seems to be capable of some ranged work, with his fire Magic, which would give him (IMO) the best odds against Kyvir depending on the fight's setting. I'd say that Alexander would do best in 50+ meters sized area, but anything less an Kyvir could get close enough to end things pretty quickly.
Garuda would be a quick fight, one way or the other. I'd assume He wouldn't attack Kyvir from a long range, as that would make it easy for Kyvir to dodge the (fairly) small explosive radius. So it'd be mid-close range, which is where they both kick ass, so It'd definitely be the most interesting.
And no I get you, I'm not arguing either.
