They changed it, now you have a little icon near inventory window to exchange Naru gear for Tuvala.
For new pen system you can exchange all 7 (weapons and armours). But they can't be enchanted with "normal" enchant, only with reform stone so: tet+1, tet+2, tet+3, tet+4, and tet+5 exchange with npc Jetina for pen.
For "old" boss tet only one with exchange coupon (one per season, so you can stay with tuvala pen and next season with next coupon exchange tuvala pen from previous season for next boss tet).
Old system is outdated and unprofitable because also give you boss tet without option to sell on mp. So new system is better because you have guaranteed pen if you collect all mats for reform stones.
What to choose? There is no clear answer to this question, I can say what the majority choose: kzarka, dandelion (no other option), kutum, dim, bheg, griffon, urugon.
Wait, I got a bit confused. So I can still exchange PEN Tuvala for TET boss gear? And all of them, or only once per season? And I'll get a guaranteed PEN boss if I enchant Tuvala (TET or PEN?) to+5 with reform stones?
Yes you can still exchange one tuvala pen for boss tet with this:
https://bdocodex.com/us/item/8056/
But it does not make sense anymore with new guaranteed PEN system with Jetina.
But also not completely. Why? Pens from Jetina = one full set (7 items) per family. So when you exchange 7 pen tuvala for 7 new tet you can't obtain more.
So if somebody really want more tets old options it's still available. Eg. for weapons for alt. Season also give you tuvala exchange weapons coupons when you use "watch" quest from Fughar. So you have free char but without gear. You can use this coupons for new char but also for others char for 3 free tet boss weapons (eg. for your main char).
So you can do a "trick" eg.
I have Archer as main.
Played season as Ranger.
Used "watch" and chose Lahn as new season class.
Got 3 tuvala exchange weapons coupons.
Not used them on Lahn.
Used on Archer.
Got 3 pen tuvala weapons for Archer.
Exchange them for 3 new boss tet for my main.
Short:
Option A:
1. You can get all 7 boss tet if you have 7 tuvala pen.
2. All 7 will be as "new" boss tet. For pen only with reform stones.
Option B:
1. One tuvala pen for one "old" boss tet with [Season] Boss Gear Exchange Coupon.
Option C (mix with option A):
1. If you want "new" boss tet weapons for other char (eg. for main char) after you use "watch" on season char you can convert tuvala pen from one class to tuvala pen other class.
But be careful tuvala weapons exchange coupuns can be used only for tuvala season. If you use stones: tuvala season -> tuvala no sesaon you can't use this coupons anymore.