is 持てる potential form or continuous tense

Question

I am learning japanese grammar via Tae Kim (http://www.guidetojapanese.org/learn/grammar). I read that to change a u-verb to potential form, replace the -u ending with a -e ending and add -ru. For example 持てる or 待てる to mean can hold or can wait.

The same verb 持つ, when conjugated to its continuous tense becomes 持っている, which is sometimes simplified to 持てる. I feel like this causes ambiguity, for example, ペンは持てる can mean "I am holding a pen" or "I can hold a pen". The question is, how does one distinguish between the 2 meanings, or is there a completely different way to say these things? I read that the topic particle (を) cannot be used with the potential form of verb, so if the sentence changes to ペンを持てる, it would most likely mean "I am holding a pen", but when the particle is は, it is unclear, at least to me

Answer 1

First, "持っている" can never be simplified to "持てる". The former one "持っている", or sometimes "持ってる" for simplified one is "have something right now", but the latter one "持てる" is "able to have".

Second, "を" can be used both potential and continuous. So as I explained above, "ペンを持っている" means "is having a pen" and "ペンを持てる" is "can have a pen"