hi lagioconda,

those are good questions,, ill have to refine my post with better upgrading info, ty for the tip,
the way i plused my gear was to use hs first, till +3, than 3 lss till +6 , than i used 6 css till +12, as this point u can use es for 13, you can either cover it with a weapon cover and a +3 bonus book of melding for 16, or use a +3 prs everyday for 16. if you use a prs or bonus book of melding its a guarnteed plus. but you can't go above 16 with either.
costumes are from the item mall, they are combined with bonus books of melding. you can use +1, +2 or +3 to get a max of +16. i got a tip from a friend,, when you are using costumes for armor if you can get +16, get 16 cause you will still get the mag def and phy def bounus, but if you use a cover and bb on a wepon to get 16 you won't get the attack bonus.. so for your weapons your better off to use prs than to use a cover on them if you plan to go to 16. costumes last a month of real time. when they are done they just come off, nothing should happen to your weapon or armor. don't try to + a weapon or armor if its either covered with a cover or using a prs.
1.) costumes are for armor, covers are for weapons, yes
2.)you can get from 13 to either 15 or 16 with a prs or a costume/cover and bonus book
3.)not really, the highest you can go for a guaranteed + is till 13, using hs till +3, lss till +6, css till +12 than es till 13.
4.)after the costumes or prs is off, you will get a message saying its no longer usable or works. prs last 24 hours, costumes and covers last 1 mon.
5.) yes, you can get as many as u want mon after mon. i have 2 in my records for later.
i hope this helps, ill work on clarifying my post tonight,, huggs and glad you asked,
