As mage against an other mage => magnus (more m def, elemental protection effect, more m atk, same crit rate)
As mage against fighter => cov (more p def, more hp, more stun resist (to verify))
Imho...Since l2 updated to gracia final, the skill reuse doesn't depend on atk/cast speed anymore. Ofc it's still important but not that much. Major Arcana is way better now for both low and high rates.
I usually buy 2 same weapons and enchant them one by one till 1 fails. I keep the highest one. I buy a new weapon and try to make it up to the same I already have (let's say +10). Once I have 2 weapons with same enchant... I go for +1 on one of them, if succeded => +1 on the lower one untill one fails. Then I start again.
On retail or low private rates servers, make it +3 and u're done lol... +4 with blessed will be enough if you really want a glow (or just augment it).
Saggitarius is indeed the most effective in the most different situations. I rather play moonlight sentinel cuz they're fast (high speed and atk. speed) but they get fast down if you can't handle them.
I'd say on high rates servers...
Saggitarius = good for all (beginners can have some frags and pro's will uber pwn)
Moonlight Sentinel = technical class (only pro's pwn with that one)
Ghost Sentinel = highest power (need to be very aggressive with that class, not for carebears, especially good at mass pvp)
I rather play Orcs or Dwarfs cuz they're funny and more "unique" though ofc Humans are the most played on high rates server. On low and mid-low ones, I'd say dwarfs cuz of spoil and craft...can't be pwnage clan without dwarfs in the clan (still on low and mid-low where mats and craft are required in order to get B+ gear).
I beleive people use more other races on servers where they can take lvl 85 with their sub.