What do you need besides a suit and a set of weapons for various encounters?
1. EP
If you use 2H weapons or 1H weapons with shields there is no sense to have EP on your main jewels. Even if you use 1H weapons without shields you may prefer to other mods on your main jewels.
So you need a special weapon and jewels to drink potions.
1.1. Jewels
You defenitely need 25 EP on each jewel (there is no much sense in using 50EP ring) but what's else?
1.1.1. Chivalry.
If you haven't 120 Chivalry it's a good idea to get it on EP-jewels. Your chance to cure high-level poison depends on you skill level. With 90 Chivalry you may fail to cure several times in a row and finally find yourself dead. So you will use your EP-jewels not only to drink poisons but also to cast some Chivalry spells (mostly Cure). (In this case you may want to add FC/FCR too so you could tocast faster).
1.1.2. DCI
If you have DCI on your main jewels you it's a good idea to get it on EP-jewels too. So you don't lose defence when you switch to EP-jewels.
(And the same reason is about defencive skills like Parrying/Bushido/Weapon Skill if you have them on your main jewels.)
1.1.3. HCI
If you have HCI on your main jewels you may want to get it on EP-jewels too. So you don't lose your chance to hit when you switch to EP-jewels (to apply a special move or leach or other hit effects while you drinking poisons).
1.2. Weapon.
If you sometimes use shields it's better to use a balanced 2H weapon because when you switch to a 1H weapon you don't take off your shield.
1.2.1. Paralize
As well as with jewels you may make your EP-weapon multipurpose. So it's a good idea to get on it a usefull special move that you haven't on your other weapons. If you don't PvM in Felucia it's good to get Paralize. Ohterwise you may want Disarm/Dismount/etc.
1.2.2. HCI/DCI
You usually needn't your statndard mods like HLL/HLD on your EP-weapon so you can get to the weapon some mods from jewels (and free up on EP-jewels some room for Chivalry/FC).
2. MR
Sometimes you need to restore mana/hp when you are out of a battle. For example, when you have just got ressurected. You can restore your hp fast using mana but how to get mana?
So it's a good idea to get some jewels with MR... And in addition to jewels you may get a weapon and a shield with MR/HPR/SR.
2.1. LRC
Usually when you got ressurected you want to cast on some spells like VE or Protection. And you will able to do this without reagents if you get LRC on your MR-jewels. You needn't 100 LRC to cast a spell without reagents. 40 LRC (20 on each jewel) gives you a dicent chance to cast a spell. And you don't worry much if you get "you haven't enough reagents..." message few times. I find it's much more practical than Arcane Boots. You may also get a Pedandt of the Mage to increase your chance for a free cast but as to me 40% is good enough.
2.2. Mage
To cast Protection you need some Magery... and your MR-jewels is a good place to get magery skill. In addition to Protection you will be able to cast Teleport (sometimes you need it to get where you want).
2.3. SC
As to MR-weapon and MR-shield usually you just want as much MR as possible. But having Spell Channaling to don't take them off when casting mage spells would be handy.
1. EP
If you use 2H weapons or 1H weapons with shields there is no sense to have EP on your main jewels. Even if you use 1H weapons without shields you may prefer to other mods on your main jewels.
So you need a special weapon and jewels to drink potions.
1.1. Jewels
You defenitely need 25 EP on each jewel (there is no much sense in using 50EP ring) but what's else?
1.1.1. Chivalry.
If you haven't 120 Chivalry it's a good idea to get it on EP-jewels. Your chance to cure high-level poison depends on you skill level. With 90 Chivalry you may fail to cure several times in a row and finally find yourself dead. So you will use your EP-jewels not only to drink poisons but also to cast some Chivalry spells (mostly Cure). (In this case you may want to add FC/FCR too so you could tocast faster).
1.1.2. DCI
If you have DCI on your main jewels you it's a good idea to get it on EP-jewels too. So you don't lose defence when you switch to EP-jewels.
(And the same reason is about defencive skills like Parrying/Bushido/Weapon Skill if you have them on your main jewels.)
1.1.3. HCI
If you have HCI on your main jewels you may want to get it on EP-jewels too. So you don't lose your chance to hit when you switch to EP-jewels (to apply a special move or leach or other hit effects while you drinking poisons).
1.2. Weapon.
If you sometimes use shields it's better to use a balanced 2H weapon because when you switch to a 1H weapon you don't take off your shield.
1.2.1. Paralize
As well as with jewels you may make your EP-weapon multipurpose. So it's a good idea to get on it a usefull special move that you haven't on your other weapons. If you don't PvM in Felucia it's good to get Paralize. Ohterwise you may want Disarm/Dismount/etc.
1.2.2. HCI/DCI
You usually needn't your statndard mods like HLL/HLD on your EP-weapon so you can get to the weapon some mods from jewels (and free up on EP-jewels some room for Chivalry/FC).
2. MR
Sometimes you need to restore mana/hp when you are out of a battle. For example, when you have just got ressurected. You can restore your hp fast using mana but how to get mana?
So it's a good idea to get some jewels with MR... And in addition to jewels you may get a weapon and a shield with MR/HPR/SR.
2.1. LRC
Usually when you got ressurected you want to cast on some spells like VE or Protection. And you will able to do this without reagents if you get LRC on your MR-jewels. You needn't 100 LRC to cast a spell without reagents. 40 LRC (20 on each jewel) gives you a dicent chance to cast a spell. And you don't worry much if you get "you haven't enough reagents..." message few times. I find it's much more practical than Arcane Boots. You may also get a Pedandt of the Mage to increase your chance for a free cast but as to me 40% is good enough.
2.2. Mage
To cast Protection you need some Magery... and your MR-jewels is a good place to get magery skill. In addition to Protection you will be able to cast Teleport (sometimes you need it to get where you want).
2.3. SC
As to MR-weapon and MR-shield usually you just want as much MR as possible. But having Spell Channaling to don't take them off when casting mage spells would be handy.